📖 Complete bibliography

Snijders, R. J. M., Noble, P., Sebire, N., Souka, A., & Nicolaides, K. H. (1998). UK multicentre project on assessment of risk of trisomy 21 by maternal age and fetal nuchal-translucency thickness at 10–14 weeks of gestation. The Lancet, 352(9125), 343–346.

Contribution: NT 95th percentile by CRL (2.1 mm at 45 mm → 2.7 mm at 84 mm) and 99th percentile of 3.5 mm, used as continuous curves.

Nicolaides, K. H., Snijders, R. J. M., & Cuckle, H. S. (1998). Correct estimation of parameters for ultrasound nuchal translucency screening. Prenatal Diagnosis, 18(5), 519–521. https://doi.org/10.1002/(SICI)1097-0223(199805)18:5<519::AID-PD398>3.0.CO;2-U

Contribution: equation for the NT median by CRL (log10 NT = −0.3599 + 0.0127·CRL − 0.000058·CRL²), used with an own CaVeSal® algorithm.

Sharifzadeh, M., Adibi, A., Kazemi, K., & Hovsepian, S. (2015). Normal reference range of fetal nuchal translucency thickness in pregnant women in the first trimester, one center study. Journal of Research in Medical Sciences, 20(10), 969–973. https://doi.org/10.4103/1735-1995.172786

Contribution: local population reference (Iran, single centre) cited in the guide for comparison only; not used in the calculation (CC BY-NC-SA licence).

Cicero, S., Curcio, P., Papageorghiou, A., Sonek, J., & Nicolaides, K. (2001). Absence of nasal bone in fetuses with trisomy 21 at 11–14 weeks of gestation: an observational study. The Lancet, 358(9294), 1665–1667.

Contribution: absent nasal bone as a first-trimester T21 marker (absent in ~60–70% of T21; in euploid fetuses 2–9% by ethnicity and CRL, Cicero 2004) — "Nasal bone" field of chromosomal screening.

Cicero, S., Rembouskos, G., Vandecruys, H., Hogg, M., & Nicolaides, K. H. (2004). Likelihood ratio for trisomy 21 in fetuses with absent nasal bone at the 11–14-week scan. Ultrasound in Obstetrics & Gynecology, 23(3), 218–223. https://doi.org/10.1002/uog.992

Contribution: frequency of absent nasal bone in T21 and euploid fetuses and its variation by ethnicity, CRL and NT — "Nasal bone" field text.

Hecht, C. A., & Hook, E. B. (1994). The imprecision in rates of Down syndrome by 1-year maternal age intervals: a critical analysis of rates used in biochemical screening. Prenatal Diagnosis, 14(8), 729–738. https://doi.org/10.1002/pd.1970140814

Contribution: term risk of T21 by maternal age, used with a CaVeSal® own algorithm for the ultrasound-only prior risk.

Nicolaides, K. H. (2011). Screening for fetal aneuploidies at 11 to 13 weeks. Prenatal Diagnosis, 31(1), 7–15. https://doi.org/10.1002/pd.2637

Contribution: frequency of absent nasal bone, reversed ductus venosus a-wave and tricuspid regurgitation in euploid and trisomic fetuses; basis of the orientative ultrasound category (low, intermediate, high).

Snijders, R. J. M., Sundberg, K., Holzgreve, W., Henry, G., & Nicolaides, K. H. (1999). Maternal age- and gestation-specific risk for trisomy 21. Ultrasound in Obstetrics & Gynecology, 13(3), 167–170. https://doi.org/10.1046/j.1469-0705.1999.13030167.x

Contribution: gestational-age adjustment of T21 risk and FMF table of T21, T18 and T13 by age and GA; used for the ultrasound-only prior risk (without ultrasound).

Kagan, K. O., Cicero, S., Staboulidou, I., Wright, D., & Nicolaides, K. H. (2009). Fetal nasal bone in screening for trisomies 21, 18 and 13 and Turner syndrome at 11–13 weeks of gestation. Ultrasound in Obstetrics & Gynecology, 33(3), 259–264.

Contribution: integration of nasal bone together with ductus venosus and tricuspid regurgitation in first-trimester combined screening.

Maiz, N., Valencia, C., Kagan, K. O., Wright, D., & Nicolaides, K. H. (2009). Ductus venosus Doppler in screening for trisomies 21, 18 and 13 and Turner syndrome at 11–13 weeks of gestation. Ultrasound in Obstetrics & Gynecology, 33(5), 512–517.

Contribution: reversed/absent ductus venosus a-wave as a marker of aneuploidy and heart disease — "Ductus venosus" field of first-trimester screening.

Medicina Fetal Barcelona (Hospital Clínic – Hospital Sant Joan de Déu – Universitat de Barcelona). Protocolo: Cribado prenatal de las anomalías cromosómicas. Última actualización 20/02/2019. fetalmedicinebarcelona.org · Programa vigente: Hospital Clínic Barcelona

Contribution: preferred risk cut-offs of combined screening (very high ≥1/10, high 1/11–1/250, intermediate 1/251–1/1100, low <1/1100) and associated management (NIPT or invasive testing, microarray) — default option of the "Risk cut-offs" selector.

Nicolaides, K. H., Spencer, K., Avgidou, K., Faiola, S., & Falcon, O. (2005). Multicenter study of first-trimester screening for trisomy 21 in 75 821 pregnancies: results and estimation of the potential impact of individual risk-orientated two-stage first-trimester screening. Ultrasound in Obstetrics & Gynecology, 25(3), 221–226. https://doi.org/10.1002/uog.1860 · PubMed 15736186

Contribution: alternative two-stage cut-offs (high ≥1/100, intermediate 1/101–1/1000 with second first-trimester ultrasound, low <1/1000) — "Nicolaides 2005 · FMF" option of the selector.

FIGO Working Group on Best Practice in Maternal-Fetal Medicine (2015). Best practice in maternal-fetal medicine. International Journal of Gynecology & Obstetrics, 128(1), 80–82. glowm.com

Contribution: variant cited only in text (manual and simulator): >1/100 cell-free fetal DNA or invasive testing, 1/101–1/2500 cell-free fetal DNA, <1/2500 none.

Fetal Medicine Foundation (FMF) / Nicolaides, K. H. The 11–13 weeks scan. Londres: Fetal Medicine Foundation.

Contribution: general methodological framework of first-trimester combined screening (NT, PAPP-A, β-hCG, additional markers) and first-trimester fetal megacystis (7 mm/15 mm cut-offs, aneuploidy risk vs. obstructive uropathy).

American College of Obstetricians and Gynecologists (ACOG). (2020). Practice Bulletin No. 222: Gestational Hypertension and Preeclampsia. Obstetrics & Gynecology, 135(6), e237–e260.

Contribution: classification of hypertensive disorders of pregnancy and severity criteria (proteinuria, vasospasm symptoms) — extended hypertension fields in "General data". Alternative aspirin regimen (81 mg/day from 12–28 wk, ideally before 16, until delivery) shown by the Calculator alongside the FIGO regimen.

Poon, L. C., Shennan, A., Hyett, J. A., et al. (2019). The International Federation of Gynecology and Obstetrics (FIGO) initiative on pre-eclampsia: A pragmatic guide for first-trimester screening and prevention. International Journal of Gynecology & Obstetrics, 145(Suppl 1), 1–33. PMC6944283

Contribution: aspirin regimen preferred by CaVeSal (~150 mg every night from 11–14+6 wk until 36 wk, delivery or diagnosis of PE), universal first-trimester combined screening and high-risk cut-off of 1 in 100. Source of the Simulator case "Preeclampsia screening and prevention".

International Society for the Study of Hypertension in Pregnancy (ISSHP). (2021). The classification, diagnosis and management of the hypertensive disorders of pregnancy: A revised statement. Pregnancy Hypertension, 27.

Contribution: harmonised diagnostic criteria for preeclampsia used in the live interpretation of PE in the 1st/2nd/3rd trimester.

FIGO Working Group on Good Clinical Practice in Maternal-Fetal Medicine. (2019). Good clinical practice advice: First trimester screening and prevention of pre-eclampsia in singleton pregnancy. International Journal of Gynecology & Obstetrics, 144(3), 325–329.

Contribution: first-trimester uterine artery PI cut-offs (≥1.90 moderate, ≥2.35 high) and framework for universal PE screening.

Gómez, O., Figueras, F., Fernández, S., et al. (2008). Reference ranges for uterine artery mean pulsatility index at 11–41 weeks of gestation. Ultrasound in Obstetrics & Gynecology, 32(2), 128–132. — Medicina Fetal Barcelona.

Contribution: reference curves of mean uterine artery PI by GA (11–41 wk): the Calculator computes the percentile and uses the P95 for the entered GA as cut-off in the 1st and 2nd trimesters.

Martin, A. M., Bindra, R., Curcio, P., Cicero, S., & Nicolaides, K. H. (2001). Screening for pre-eclampsia and fetal growth restriction by uterine artery Doppler at 11–14 weeks of gestation. Ultrasound in Obstetrics & Gynecology, 18(6), 583–586.

Contribution: 95th centile of 2.35 for mean uterine artery PI at 11–14 wk; used only when GA is not entered.

Gana, N., Sarno, M., Vieira, N., Wright, A., Charakida, M., & Nicolaides, K. H. (2022). Ophthalmic artery Doppler at 11–13 weeks' gestation in prediction of pre-eclampsia. Ultrasound in Obstetrics & Gynecology, 59(6), 731–736.

Contribution: ophthalmic artery PSV2/PSV1 ratio at 11–13 wk as a complementary element of preeclampsia screening; no single validated cut-off and no aspirin indication on its own.

de Oliveira, C. A., et al. (2013). Changes in ophthalmic artery Doppler indices in hypertensive disorders during pregnancy. Journal of Ultrasound in Medicine, 32(4), 609–616.

Contribution: ophthalmic artery PSV2/PSV1 ratio ≥0.78 associated with preeclampsia with severe features (2nd/3rd trimester).

Diniz, A. L. D., Moron, A. F., dos Santos, M. C., Sass, N., Pires, C. R., & Debs, C. L. (2008). Ophthalmic artery Doppler as a measure of severe pre-eclampsia. International Journal of Gynecology & Obstetrics, 100(3), 216–220.

Contribution: ophthalmic artery Doppler to differentiate mild from severe preeclampsia; supports the prognostic use of the ratio in the 2nd/3rd trimester.

Verlohren, S., Stepan, H., & Dechend, R. (2012). Angiogenic growth factors in the diagnosis and prediction of pre-eclampsia. Clinical Science, 122(2), 43–52.

Contribution: pathophysiological framework of the sFlt-1/PlGF ratio and its diagnostic/prognostic role in preeclampsia.

Roche Diagnostics / BRAHMS Thermo Fisher Scientific. Elecsys® sFlt-1/PlGF ratio — guía de interpretación clínica (corte ≤38 descarta PE a corto plazo; 38–85/110 zona gris EG-dependiente; >85/110 sospecha; >655 PE inminente).

Contribution: exact numerical cut-offs of the sFlt-1/PlGF ratio used by the Calculator, with their GA dependence (cut-off 85 before 34 weeks, 110 from 34 weeks).

International Association of Diabetes and Pregnancy Study Groups (IADPSG) Consensus Panel. (2010). International association of diabetes and pregnancy study groups recommendations on the diagnosis and classification of hyperglycemia in pregnancy. Diabetes Care, 33(3), 676–682.

Contribution: one-step protocol (75 g): fasting ≥92, 1 h ≥180, 2 h ≥153 mg/dL, one value is enough — "IADPSG/WHO/ADA" button in the Calculator.

American Diabetes Association Professional Practice Committee. (2026). 2. Diagnosis and classification of diabetes: Standards of Care in Diabetes—2026. Diabetes Care, 49(Suppl. 1). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12690183

Contribution: Table 2.8 in force: IADPSG thresholds for one-step; two-step with 50 g ≥130/135/140 and 100 g Carpenter-Coustan; rec. 2.31b: before 15 weeks, fasting 110–125 or HbA1c 5.9–6.4% = early abnormal glucose metabolism; postpartum OGTT at 4–12 weeks.

American Diabetes Association Professional Practice Committee. (2026). 15. Management of diabetes in pregnancy: Standards of Care in Diabetes—2026. Diabetes Care, 49(Suppl. 1). https://pmc.ncbi.nlm.nih.gov/articles/PMC12690181/

Contribution: TOBOGM and early treatment by shared decision; targets <95 / <140 / <120; metformin does not prevent GDM (meta-analysis of 11 RCTs).

World Health Organization. (2013). Diagnostic criteria and classification of hyperglycaemia first detected in pregnancy (WHO/NMH/MND/13.2). Geneva: WHO. https://iris.who.int/server/api/core/bitstreams/612e0faa-04b5-4984-abcb-5fe3b1703677/content

Contribution: adopts the IADPSG thresholds (92/180/153) and early fasting 92–125 as GDM.

Salzberg, S., et al. (2016). Guías de diagnóstico y tratamiento de diabetes gestacional. ALAD 2016. Revista de la ALAD, 6, 155–169. https://www.revistasad.com/index.php/diabetes/article/view/180

Contribution: ALAD criterion: fasting 100–125 mg/dL on two occasions and/or 2 h ≥140 mg/dL on the 75 g OGTT — third protocol button. Replaces the former ALAD 2019 citation (type 2 diabetes guideline).

Ministerio de Salud Pública y Bienestar Social (MSPyBS). Manual Nacional Prenatal · Flujograma de manejo de la hiperglucemia en el embarazo. Asunción, Paraguay. https://www.mspbs.gov.py/dependencias/progsalud/adjunto/59c707-ManualNacionalPrenatal.pdf · https://informacionpublica.paraguay.gov.py/public/798580-FLUJOGRAMADEMANEJODELAHIPERGLUCEMIAENELEMBARAZOpdf-FLUJOGRAMADEMANEJODELAHIPERGLUCEMIAENELEMBARAZO.pdf

Contribution: national standard (Paraguay): fasting ≥92 at the first visit = GDM; 75 g OGTT from week 24; 2 h 140–152 = high risk of developing diabetes.

Simmons, D., Immanuel, J., Hague, W. M., et al. (2023). Treatment of gestational diabetes mellitus diagnosed early in pregnancy (TOBOGM). New England Journal of Medicine, 388(23), 2132–2144. https://www.nejm.org/doi/full/10.1056/NEJMoa2214956

Contribution: early glucose band: benefit in the higher band and possible excess SGA when treating the lower band — basis of the two readings before 15 weeks.

Sweeting, A., Hare, M. J. L., de Jersey, S. J., et al. (2025). Australasian Diabetes in Pregnancy Society (ADIPS) 2025 consensus recommendations for the screening, diagnosis and classification of gestational diabetes. Medical Journal of Australia, 223(3). https://www.mja.com.au/system/files/issues/223_03/mja252696.pdf

Contribution: Australian thresholds 95/191/162 mg/dL, mentioned in the guides as a reference.

American Diabetes Association Professional Practice Committee. (2026). Standards of Care in Diabetes—2026. Diabetes Care.

Contribution: annual update of diagnostic criteria and management of GDM used as the current reference.

American Thyroid Association (ATA). Alexander, E. K., Pearce, E. N., Brent, G. A., et al. (2017). 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum. Thyroid, 27(3), 315–389.

Contribution: use the laboratory pregnancy range; if not reported, TSH upper limit 4.0 mU/L. Levothyroxine if TSH >4.0 with anti-TPO+ or TSH ≥10; consider with TSH 2.5–4.0 and anti-TPO+. Low FT4 with normal TSH (isolated hypothyroxinaemia) is not routinely treated. Grey zone (CaVeSal® suggestion): TSH >2.5 in 1T or >3.0 in 2T–3T, check anti-TPO (rec. 28). Preconception: TSH between the lower limit and 2.5; IVF/ICSI with subclinical hypothyroidism, goal <2.5 (rec. 20).

Institute of Medicine (IOM) / National Academy of Sciences (NAS). (2009). Weight Gain During Pregnancy: Reexamining the Guidelines. Washington, DC: National Academies Press.

Contribution: targets for total gestational weight gain and weekly rate by pre-pregnancy BMI category.

World Health Organization (WHO); American College of Obstetricians and Gynecologists (ACOG); FIGO; Endocrine Society (2024); EBCOG (2024); Cochrane Pregnancy and Childbirth Group.

Contribution: doses of folic acid/methylfolate, iron, calcium, iodine and omega-3/DHA in the "Recommended supplementation" of the comprehensive risk report.

Cluver CA, Rohwer C, Rohwer AC. (2025). Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems. Cochrane Database of Systematic Reviews, 12, CD001059. PubMed 41330480 · doi:10.1002/14651858.CD001059.pub6

Contribution: calcium: no difference in pre-eclampsia in the large trials (RR 0.92; high certainty); shown alongside the WHO position.

World Health Organization. (2012). Guideline: Daily iron and folic acid supplementation in pregnant women. OMS IRIS

Contribution: prophylactic iron 30–60 mg/day; anaemia: 120 mg/day elemental iron until Hb normalises.

Middleton P, Gomersall JC, Gould JF, et al. (2018). Omega-3 fatty acid addition during pregnancy. Cochrane Database of Systematic Reviews, 11, CD003402. Cochrane Library

Contribution: omega-3: 42% fewer births <34 wk (RR 0.58); uncertain effect on pre-eclampsia.

National Institutes of Health, Office of Dietary Supplements. Dietary Supplements and Life Stages: Pregnancy (Health Professional Fact Sheet; includes CDC on MTHFR and IOM 2011 on calcium). NIH ODS

Contribution: MTHFR: CDC keeps folic acid (the only form proven to prevent NTDs); calcium 1000 mg/day (1300 under 19), the same as outside pregnancy.

American College of Obstetricians and Gynecologists. (2017). Practice Bulletin No. 187: Neural Tube Defects. Obstetrics & Gynecology, 130(6), e279–e290. PubMed 29189693

Contribution: Previous NTD: folic acid 4 mg/day (NICE and RCOG: 5 mg/day) from 3 months before conception (minimum 1) to 12 wk, then standard dose; also if the woman or her partner has an NTD; genetic counselling and targeted ultrasound.

Robinson, H. P., & Fleming, J. E. E. (1975). A critical evaluation of sonar "crown-rump length" measurements. British Journal of Obstetrics and Gynaecology, 82(9), 702–710.

Contribution: CRL dating formula (GA in days = 8.052×√(CRL×1.037)+23.73) used in "GA by CRL — 1st trimester".

Hadlock, F. P., Harrist, R. B., Sharman, R. S., Deter, R. L., & Park, S. K. (1985). Estimation of fetal weight with the use of head, body, and femur measurements—a prospective study. American Journal of Obstetrics and Gynecology, 151(3), 333–337.

Contribution: "Biometry → Hadlock" EFW mode: 4-parameter (BPD, HC, AC, FL), 3-parameter (HC, AC, FL / BPD, AC, FL) and 2-parameter (AC, FL) formulas.

Hadlock, F. P., Deter, R. L., Harrist, R. B., & Park, S. K. (1984). Estimating fetal age: computer-assisted analysis of multiple fetal growth parameters. Radiology, 152(2), 497–501.

Contribution: GA formulas from BPD, HC, AC and FL and mean GA in "Biometry · 2T/3T".

Chitty, L. S., Altman, D. G., Henderson, A., & Campbell, S. (1994). Charts of fetal size: 2. Head measurements. British Journal of Obstetrics and Gynaecology, 101(1), 35–43. https://doi.org/10.1111/j.1471-0528.1994.tb13007.x

Contribution: mean and SD equations of head circumference (derived HC) by GA — exact HC centile and HC Z-score (suspected microcephaly <−2 SD, microcephaly <−3 SD) in the asymmetry module.

ISUOG. (n.d.). Microcephaly. VISUOG — Obstetrics: brain, abnormal cephalic measurements. https://www.isuog.org/education/visuog/obstetrics/brain/abnormal-cephalic-measurements/microcephaly.html

Contribution: Basis for the prenatal microcephaly cutoffs: suspected <−2 SD, microcephaly <−3 SD.

World Health Organization. (2016). Assessment of infants with microcephaly in the context of Zika virus: interim guidance (WHO/ZIKV/MOC/16.3). https://iris.who.int/bitstream/handle/10665/204475/WHO_ZIKV_MOC_16.3_eng.pdf

Contribution: Definition of microcephaly (<−2 SD) and severe microcephaly (<−3 SD); supports showing both cutoffs.

Staples, J. E., Dziuban, E. J., Fischer, M., et al. (2016). Interim guidelines for the evaluation and testing of infants with possible congenital Zika virus infection — United States, 2016. MMWR, 65(3), 63–67. https://www.cdc.gov/mmwr/volumes/65/wr/mm6503e3.htm

Contribution: Neonatal definition of microcephaly <P3 during Zika; shown as a reference, not as a prenatal cutoff.

Chitty, L. S., & Altman, D. G. (2002). Charts of fetal size: limb bones. BJOG: An International Journal of Obstetrics & Gynaecology, 109(8), 919–929.

Contribution: mean and SD equations for humerus and femur length by GA — GA estimated by humerus/femur, centile for GA (entering LMP or early scan) and short-bone alert <3rd centile.

Snijders, R. J. M., & Nicolaides, K. H. (1994). Fetal biometry at 14–40 weeks' gestation. Ultrasound in Obstetrics & Gynecology, 4(1), 34–48.

Contribution: reference equation of the transverse cerebellar diameter by GA — GA estimated by TCD, centile for GA (entering LMP or early scan) and TCD <5th centile alert. The rule TCD (mm) ≈ GA holds only up to 20–21 wk.

Campbell, S., & Thoms, A. (1977). Ultrasound measurement of the fetal head to abdomen circumference ratio in the assessment of growth retardation. British Journal of Obstetrics and Gynaecology, 84(3), 165–174.

Contribution: concept of head-abdomen asymmetry (HC/AC ratio) in late FGR (brain sparing).

Hadlock, F. P., Deter, R. L., Harrist, R. B., Roecker, E., & Park, S. K. (1983). A date-independent predictor of intrauterine growth retardation: femur length/abdominal circumference ratio. American Journal of Roentgenology, 141(5), 979–984.

Contribution: GA-independent FL/AC ratio: normal 0.20–0.235 (22 ± 2%); >0.235 suggests asymmetric FGR — "FL/AC Asymmetry" tab.

Figueras, F., Meler, E., Iraola, A., Eixarch, E., Coll, O., Figueras, J., Francis, A., Gratacós, E., & Gardosi, J. (2008). Customized birthweight standards for a Spanish population. European Journal of Obstetrics & Gynecology and Reproductive Biology, 136(1), 20–24. https://doi.org/10.1016/j.ejogrb.2006.12.015

Contribution: sex-adjusted term weight and proportionality curve for the "Figueras 2008" EFW percentile chart (Own algorithm CaVeSal®: own code, fetal sex adjustment and correction of ultrasound estimation bias).

Figueras, F., & Gratacós, E. (2008). An integrated approach to fetal growth restriction. Best Practice & Research Clinical Obstetrics & Gynaecology, 22(1), 147–158. — and its update as the Fetal Medicine Barcelona (MFB) Protocol, November 2024.

Contribution: SGA/AGA/LGA/FGR classification combining EFW percentile + fetal Doppler + mean uterine artery PI.

Stirnemann, J., Salomon, L. J., & Papageorghiou, A. T. (2020). INTERGROWTH-21st standards for Hadlock's estimation of fetal weight. Ultrasound in Obstetrics & Gynecology, 56(6), 946–948. https://doi.org/10.1002/uog.22000

Contribution: published equations (Table S1) of the INTERGROWTH-21st standard for 3-parameter Hadlock EFW (HC, AC, FL), 18–40 wk (up to 41 if justified) — "INTERGROWTH-21st 2020" EFW chart (Own algorithm CaVeSal®: own code with the original equations).

Baschat, A. A., & Gembruch, U. (2003). The cerebroplacental Doppler ratio revisited. Ultrasound in Obstetrics & Gynecology, 21(2), 124–127.

Contribution: concept of the cerebroplacental ratio (CPR = MCA/UA) as a marker of cerebral redistribution. No longer used for the centile, which now follows the FMF model of Ciobanu 2019.

Ciobanu, A., Wright, A., Syngelaki, A., Wright, D., Akolekar, R., & Nicolaides, K. H. (2019). Fetal Medicine Foundation reference ranges for umbilical artery and middle cerebral artery pulsatility index and cerebroplacental ratio. Ultrasound in Obstetrics & Gynecology, 53(4), 465–472.

Contribution: FMF reference model (log10-Gaussian distribution) of umbilical artery PI, MCA PI and cerebroplacental ratio by GA. The Calculator computes the centile with its own equations fitted to that model (maximum error 0.001), without reproducing tables.

Baschat, A. A. (2011). Neurodevelopment following fetal growth restriction and its relationship with antepartum parameters of placental dysfunction. Ultrasound in Obstetrics & Gynecology, 37(5), 501–514.

Contribution: sequence of Doppler deterioration in severe FGR (ductus venosus, tricuspid regurgitation, aortic isthmus, pulsatile umbilical vein) — framework of "Advanced haemodynamic Doppler".

TRUFFLE Study Group. Lees, C. C., Marlow, N., van Wassenaer-Leemhuis, A., et al. (2015). 2 year neurodevelopmental and intermediate perinatal outcomes in infants with very preterm fetal growth restriction (TRUFFLE): a randomised trial. The Lancet, 385(9983), 2162–2172.

Contribution: clinical validation of the ductus venosus as a delivery criterion in severe preterm FGR, and of follow-up with advanced Doppler.

Gratacós, E., & Torres, X. — Protocolo de Doppler fetal avanzado, Medicina Fetal Barcelona (2023, actualización interna del servicio).

Contribution: practical integration of the aortic isthmus and pulsatile umbilical vein into FGR follow-up in the reference care network for Latin America.

ISUOG Practice Guidelines: use of Doppler ultrasonography in obstetrics. (2020). Ultrasound in Obstetrics & Gynecology, 56(2), 298–312.

Contribution: technical standardisation of all Doppler measurements in the Calculator (angle of insonation, sampling site) and their clinical interpretation.

American College of Obstetricians and Gynecologists (ACOG). Practice Bulletin No. 127: Management of Preterm Labor. · Royal College of Obstetricians and Gynaecologists (RCOG). Green-top Guideline No. 7: Antenatal Corticosteroids to Reduce Neonatal Morbidity and Mortality.

Contribution: fetal lung maturation regimen with betamethasone (12 mg IM every 24 h × 2 doses) recalled when advanced Doppler becomes abnormal at <34 weeks.

International Society of Ultrasound in Obstetrics and Gynecology (ISUOG). Practice Guidelines (updated): performance of the routine mid-trimester fetal ultrasound scan. (2022). Ultrasound in Obstetrics & Gynecology, 59(6), 840–856. — y su antecesora, ISUOG Practice Guidelines: sonographic examination of the fetal central nervous system (2020) y fetal heart screening examination (2023).

Contribution: technical framework and checklist by system of the second-trimester anomaly scan (CNS, face, spine, heart, abdomen, limbs) that structures the whole "Anomaly scan" section of the Calculator.

Paladini, D., & Volpe, P. (2018). Ultrasound of Congenital Fetal Anomalies: Differential Diagnosis and Prognostic Indicators (3.ª ed.). CRC Press.

Contribution: detailed diagnostic criteria and management of each structural finding in the Calculator (ventriculomegaly, lemon/strawberry sign, heart defects, CDH, abdominal wall defects).

Jeanty, P., Dramaix-Wilmet, M., Elkhazen, N., Hubinont, C., & van Regemorter, N. (1984). Measurements of fetal orbits and binocular distance in normal pregnancy. Journal of Ultrasound in Medicine, 3(6), 241–244.

Contribution: reference tables by GA of IOD/BOD (inner and binocular orbital diameters), weeks 16 to 32 — "Orbital diameters" field in Face.

Mayden, K. L., Tortora, M., Berkowitz, R. L., Bracken, M., & Hobbins, J. C. (1982). Orbital diameters: a new parameter for prenatal diagnosis and dating. American Journal of Obstetrics and Gynecology, 144(3), 289–297.

Contribution: "rule of thirds" (IOD:OD:IOD ≈ 1:1:1) used for the automatic classification of the IOD/BOD ratio (>0.40 hypertelorism, <0.25 hypotelorism) and screening for microphthalmia.

Corteville, J. E., Gray, D. L., & Crane, J. P. (1991). Congenital hydronephrosis: correlation of fetal ultrasonographic findings with infant outcome. American Journal of Obstetrics and Gynecology, 165(2), 384–388. · Corteville, J. E., Dicke, J. M., & Crane, J. P. (1992). Fetal pyelectasis and Down syndrome: is genetic amniocentesis warranted? Obstetrics & Gynecology, 79(5), 770–772.

Contribution: renal pelvis dilation cut-offs by AP diameter (normal/mild/obstructive, with a GA-dependent cut-off at 33 weeks) used in "Abdomen".

Vinkesteijn, A. S. M., Mulder, P. G. H., & Wladimiroff, J. W. (2001). Fetal transverse cerebellar diameter measurements in normal and reduced fetal growth. Ultrasound in Obstetrics & Gynecology, 15(1), 47–51.

Contribution: shows that the real standard for TCD (CNS, morphology) is a p5–p95 percentile table by GA, not an absolute difference in mm — this led to removing a poorly founded automatic alert in an earlier pass.

CDHSG — Congenital Diaphragmatic Hernia Study Group / Jani, J., Nicolaides, K. H., Keller, R. L., et al. (2007). Observed to expected lung area to head circumference ratio in the prediction of survival in fetuses with isolated diaphragmatic hernia. Ultrasound in Obstetrics & Gynecology, 30(1), 67–71. · Deprest, J., Nicolaides, K., & Gratacos, E. — TOTAL Trial Group (Tracheal Occlusion To Accelerate Lung growth).

Contribution: O/E LHR as a predictor of severity in congenital diaphragmatic hernia (<25% severe, 25–44.9% moderate —35–44.9% with liver herniation—, ≥45% favourable).

Sirilert, S., Charoenratana, C., Tongsong, T. (2019). Fetal Cardiothoracic Ratio Reference Range at Gestational Age 14–40 Weeks. Journal of Ultrasound in Medicine, 38(4), 999–1007. · Leung, K. Y., Mak, S. L., Ngai, C. S. W., et al. (2006). Standard scanning plane for measurement of fetal cardiac transverse diameter and cardiothoracic ratio. Ultrasound in Obstetrics & Gynecology, 28(2), 173–177.

Contribution: cardiothoracic index cut-offs by circumferences/diameters, GA-dependent (>0.50 at 12–15 wk · >0.52 at 18–20 wk · >0.59 at 25–30 wk).

Jauniaux, E., Bhide, A., Kennedy, A., et al. — FIGO Placenta Accreta Spectrum Expert Consensus Panel. (2018). FIGO consensus guidelines on placenta accreta spectrum disorders: Prenatal diagnosis and screening. International Journal of Gynecology & Obstetrics, 140(3), 274–280. · FIGO Placenta Accreta Spectrum Expert Consensus Panel (2018). Conservative management. IJGO, 140(3), 291–298.

Contribution: risk factors (previous caesareans, curettage, uterine surgery, Asherman), 2D ultrasound signs and FIGO surgical/histopathological classification (grades 1 to 3b) of PAS.

Jauniaux, E., Collins, S., & Burton, G. J. (2016). Placenta accreta spectrum: pathophysiology and evidence-based anatomy for prenatal ultrasound imaging. American Journal of Obstetrics and Gynecology, 215(3), 712–721.

Contribution: pathological correlate of the "clear zone", myometrial thinning and placental lacunae — basis of the Calculator's 2D signs.

Collins, S. L., Ashcroft, A., Braun, T., et al. — European Working Group on Abnormally Invasive Placenta (EW-AIP). (2016). Proposal for standardized ultrasound descriptors of abnormally invasive placenta (AIP). Ultrasound in Obstetrics & Gynecology, 47(3), 271–275.

Contribution: standardisation of colour Doppler signs (uterovesical/subplacental hypervascularity, bridging vessels, lacunae feeder vessels).

American College of Obstetricians and Gynecologists (ACOG) & Society for Maternal-Fetal Medicine (SMFM). (2018, reafirmado 2021). Obstetric Care Consensus No. 7: Placenta Accreta Spectrum. Obstetrics & Gynecology, 132(6), e259–e275.

Contribution: management of suspected PAS (never manual removal, placenta in situ + en bloc hysterectomy, Level III-IV centre, planned caesarean at 34+0–35+6 wk) — "golden rule" cited in the Calculator.

Ministerio de Salud Pública y Bienestar Social (MSPyBS). Manual Nacional de Normas de Atención de las Principales Patologías Obstétricas. Asunción, Paraguay.

Contribution: local adoption of the recommended surgical management in confirmed accreta.

ESHRE Guideline Group on RPL; Bender Atik R, et al. (2023). ESHRE guideline: recurrent pregnancy loss: an update in 2022. Human Reproduction Open, 2023(1), hoad002. doi:10.1093/hropen/hoad002

Contribution: recurrent pregnancy loss (2 or more losses): antiphospholipid work-up, TSH and anti-TPO.

Rink BD, Dugoff L, Kuller JA. (2025). Society for Maternal-Fetal Medicine Consult Series #74: cell-free DNA screening for aneuploidies: updated guidance. Pregnancy, 1, e70139. doi:10.1002/pmf2.70139 · American College of Obstetricians and Gynecologists. (2026). Practice Advisory: Screening for Fetal Chromosomal Abnormalities (replaces PB 226). ACOG

Contribution: management of a normal 1st-trimester screen and low-risk cell-free DNA (screening, not diagnosis; offer it to every pregnant patient).

American College of Obstetricians and Gynecologists. (2020). Committee Opinion No. 797: Prevention of Group B Streptococcal Early-Onset Disease in Newborns. Obstetrics & Gynecology, 135(2), e51–e72. PubMed 31977795

Contribution: negative group B streptococcus: no intrapartum prophylaxis; culture valid for 5 weeks.

Schillie S, Vellozzi C, Reingold A, et al. (2018). Prevention of Hepatitis B Virus Infection in the United States: Recommendations of the Advisory Committee on Immunization Practices. MMWR Recommendations and Reports, 67(1), 1–31. CDC MMWR

Contribution: negative anti-HBs: hepatitis B vaccine is safe in pregnancy.

Centers for Disease Control and Prevention (CDC). (2024). Hepatitis B vaccine administration: pregnancy. https://www.cdc.gov/hepatitis-b/hcp/vaccine-administration/index.html

Contribution: vaccines usable in pregnancy: Engerix-B, Recombivax HB, Twinrix or Heplisav-B; PreHevbrio withdrawn from the market.

Organización Mundial de la Salud. Calcium supplementation during pregnancy to reduce the risk of pre-eclampsia (e-Library of Evidence for Nutrition Actions, eLENA). OMS eLENA · Dwarkanath P, Muhihi A, Sudfeld CR, et al. (2024). Two Randomized Trials of Low-Dose Calcium Supplementation in Pregnancy. New England Journal of Medicine, 390(2), 143–153. NEJM

Contribution: calcium 1.5–2 g/day in 3 doses in low-intake populations; 500 mg/day non-inferior to 1500 mg/day.

Effect of grand multiparity on adverse maternal outcomes: a prospective cohort study. (2022). Frontiers in Public Health. PMC9608575 (FIGO definition: 5 or more births)

Contribution: grand multiparity: higher risk of postpartum haemorrhage and malpresentation.

Equipo clínico CaVeSal® (Dr. Carlos Vera Salerno). "Clasificación CaVeSal" — esquema propio de puntaje (0–9 con exención, Probabilidad Baja/Intermedia/Alta, Extensión Focal/Difusa) que combina factores de riesgo + signos 2D + signos Doppler color.

Contribution: the team's own scheme, NOT a published FIGO/ISUOG/ACOG score — it is the formula that actually calculates Probability and Extent in the Calculator result.

Mari, G., Deter, R. L., Carpenter, R. L., et al. — Collaborative Group for Doppler Assessment of the Blood Velocity in Anemic Fetuses. (2000). Noninvasive diagnosis by Doppler ultrasonography of fetal anemia due to maternal red-cell alloimmunization. New England Journal of Medicine, 342(1), 9–14.

Contribution: equation of the median MCA-PSV by GA and cut-offs 1.29 (mild) and 1.50 MoM (moderate-severe) — basis of the "MCA Doppler — Fetal anaemia" module.

Detti, L., Oz, U., Guney, I., Ferguson, J. E., Bahado-Singh, R. O., & Mari, G. — Collaborative Group for Doppler Assessment of the Blood Velocity in Anemic Fetuses. (2002). Doppler ultrasound velocimetry for timing the second intrauterine transfusion in fetuses with anemia from red cell alloimmunization. American Journal of Obstetrics and Gynecology, 187(4), 1048–1051.

Contribution: practical validation of serial MCA-PSV follow-up between intrauterine transfusions.

Gratacós, E., Lewi, L., Muñoz, B., et al. (2007). A classification system for selective intrauterine growth restriction in monochorionic pregnancies according to umbilical artery Doppler flow in the smaller twin. Ultrasound in Obstetrics & Gynecology, 30(1), 28–34.

Contribution: classification of selective FGR in monochorionic twins by the umbilical artery Doppler pattern of the smaller twin.

Torres, X., Chavez, M., Castillo, J., & Rolle, V. (2017). Perinatal outcomes of monochorionic twin pregnancies. Fetal Diagnosis and Therapy. · ISUOG Practice Guidelines: role of ultrasound in twin pregnancy (2016/2020). Ultrasound in Obstetrics & Gynecology.

Contribution: general framework for ultrasound/Doppler follow-up of monochorionic twin pregnancy.

Manning, F. A., Platt, L. D., & Sipos, L. (1980). Antepartum fetal evaluation: development of a fetal biophysical profile score. American Journal of Obstetrics and Gynecology, 136(6), 787–795.

Contribution: the 5 fetal biophysical parameters (fetal breathing movements, fetal body movements, tone, NST, amniotic fluid) and the "Complete" mode (10 points) of the BPP.

Vintzileos, A. M., Campbell, W. A., Ingardia, C. J., & Nochimson, D. J. (1983). The fetal biophysical profile and its predictive value. Obstetrics & Gynecology, 62(3), 271–278.

Contribution: "Vintzileos" mode (0/1/2 grading + Grannum placental grade, up to 12 points) of the BPP.

Clark, S. L., Sabey, P., & Jolley, K. (1989). Nonstress testing with acoustic stimulation and amniotic fluid volume assessment: 5973 tests without unexpected fetal death. American Journal of Obstetrics and Gynecology, 160(3), 694–697.

Contribution: "Abbreviated" mode of the BPP (NST + amniotic fluid, without the full ultrasound variables).

Queenan, J. T., Spong, C. Y., & Lockwood, C. J. (Eds.). Queenan's Management of High-Risk Pregnancy: An Evidence-Based Approach (7.ª ed.). Wiley-Blackwell.

Contribution: stepwise decision tree of the BPP (management by score × amniotic fluid status × GA) implemented in the Calculator.

Ministerio de Salud Pública y Bienestar Social (MSPyBS) Paraguay. Manual de Cuidados Perinatales.

Contribution: 2-hour reassessment window (alternative to 12–24 h) for intermediate scores with normal fluid, adopted locally.

Ayres-de-Campos, D., Spong, C. Y., Chandraharan, E., & FIGO Intrapartum Fetal Monitoring Expert Consensus Panel. (2015). FIGO consensus guidelines on intrapartum fetal monitoring: Cardiotocography. International Journal of Gynecology & Obstetrics, 131(1), 13–24.

Contribution: current official nomenclature of baseline FHR, variability and tracing classification — basis of the Fetal monitoring module.

American College of Obstetricians and Gynecologists (ACOG). Practice Bulletin No. 229: Fetal Heart Rate Monitoring. · ACOG Practice Bulletin No. 106: Intrapartum Fetal Heart Rate Monitoring.

Contribution: reactivity criteria (15×15 ≥32 wk / 10×10 <32 wk) and classification of tachycardia/bradycardia (>160/<110 bpm) in Fetal monitoring.

Caldeyro-Barcia, R., Casacuberta, C., Bustos, R., et al. (1966). Correlation of intrauterine pressure and fetal heart rate patterns. En: Proceedings of the Second International Conference on the Fetus and Newborn. Annals of the New York Academy of Sciences.

Contribution: classical classification of decelerations (Dips I/II/III) and "soft waves" — Dips field of Fetal monitoring.

Welt, A. M., Hobbins, J. C., & Jones, O. (1984). Biphasic variable decelerations: the "W" sign. American Journal of Obstetrics and Gynecology.

Contribution: the only real and verified reference for the "W sign" as a published pattern (biphasic variable deceleration) — distinct from "lambda waves"/"omega pattern", which the Calculator explicitly marks as informal visual analogies, not FIGO/ACOG/NICHD nomenclature.

Dawes, G. S., Redman, C. W. G., et al. — Oxford computerized CTG system. (1981/1992). Numerical analysis of the human fetal heart rate: the quality of ultrasound records. American Journal of Obstetrics and Gynecology.

Contribution: distinction between "shoulders" (reassuring, intact baroreflex) and "overshoot" (NOT reassuring, associated with developing hypoxia) in Fetal monitoring.

Society for Maternal-Fetal Medicine (SMFM). Dashe, J. S., Pressman, E. K., & Hibbard, J. U. (2018; reaffirmed 2024). SMFM Consult Series #46: Evaluation and management of polyhydramnios. American Journal of Obstetrics and Gynecology, 219(4), B2–B8. https://doi.org/10.1016/j.ajog.2018.07.016

Contribution: definition of polyhydramnios (DVP ≥8 cm or AFI ≥24 cm) and its mild/moderate/severe grading, used in the Calculator's ACOG/SMFM table.

American College of Obstetricians and Gynecologists (ACOG). (2021). Practice Bulletin No. 229: Antepartum Fetal Surveillance. Obstetrics & Gynecology, 137(6), e116–e127. · Phelan, J. P., Smith, C. V., Broussard, P., & Small, M. (1987). Amniotic fluid volume assessment with the four-quadrant technique at 36–42 weeks' gestation. Journal of Reproductive Medicine, 32(7), 540–542.

Contribution: ACOG PB 229: oligohydramnios by DVP ≤2 cm (preferred) or AFI ≤5 cm. Phelan 1987: four-quadrant AFI technique and lower borderline zone 5.1–8.0 cm. The upper borderline zone (18.1–23.9 cm) is a CaVeSal® suggestion.

International Society of Ultrasound in Obstetrics and Gynecology (ISUOG). Khalil, A., Sotiriadis, A., D'Antonio, F., et al. (2024). ISUOG Practice Guidelines: performance of third-trimester obstetric ultrasound scan. Ultrasound in Obstetrics & Gynecology, 63(1), 131–147. https://doi.org/10.1002/uog.27538

Contribution: classical absolute AFI/deepest pocket cut-offs (ISUOG 2024), second classification table available in the Calculator.

American College of Obstetricians and Gynecologists (ACOG). Practice Bulletin No. 127: Management of Preterm Labor. · Royal College of Obstetricians and Gynaecologists (RCOG). Green-top Guideline No. 7: Antenatal Corticosteroids to Reduce Neonatal Morbidity and Mortality.

Contribution: fetal lung maturation regimen (betamethasone 12 mg IM every 24 h × 2 doses) recalled in advanced Doppler, EFW/preterm mode of delivery and BPP/monitoring with an indication for delivery.

American College of Obstetricians and Gynecologists (ACOG). Practice Bulletin No. 455: Magnesium Sulfate Use in Obstetrics. · World Health Organization (WHO). (2015). WHO Recommendations on Interventions to Improve Preterm Birth Outcomes.

Contribution: fetal neuroprotection with magnesium sulfate at <32 weeks, recalled together with lung maturation in the same scenarios.

Programa ETMI Plus Paraguay. (2024). Guía para la eliminación de la transmisión materno-infantil de VIH, sífilis, hepatitis B y enfermedad de Chagas. Ministerio de Salud Pública y Bienestar Social. · Department of Health and Human Services (DHHS). (2024). Recommendations for the Use of Antiretroviral Drugs in Pregnant Women with HIV Infection.

Contribution: HIV confirmation algorithm (rapid test/ELISA + Western Blot) and start of ART aiming at an undetectable viral load at delivery.

Centers for Disease Control and Prevention (CDC). (2021). Sexually Transmitted Infections Treatment Guidelines. MMWR Recommendations and Reports, 70(4). · Organización Panamericana de la Salud (OPS). (2024). Marco para la eliminación de la transmisión materno-infantil de sífilis.

Contribution: the 4 scenarios of syphilis serological interpretation (treponemal/VDRL concordant or discordant) and the benzathine penicillin G regimen by stage.

Montoya, J. G., & Remington, J. S. (2008). Management of Toxoplasma gondii infection during pregnancy. Clinical Infectious Diseases, 47(4), 554–566.

Contribution: interpretation of toxoplasmosis IgG/IgM/IgG avidity by trimester.

Rawlinson, W. D., Boppana, S. B., Fowler, K. B., et al. (2017). Congenital cytomegalovirus infection in pregnancy and the neonate: consensus recommendations for prevention, diagnosis, and therapy. The Lancet Infectious Diseases, 17(6), e177–e188. · Leruez-Ville, M., Foulon, I., Pass, R., & Ville, Y. (2020). Cytomegalovirus infection during pregnancy: state of the science. American Journal of Obstetrics and Gynecology, 223(3), 330–349.

Contribution: interpretation of CMV IgG/IgM/IgG avidity.

Organización Panamericana de la Salud (OPS). (2023). Marco para la eliminación de la transmisión materno-infantil de la enfermedad de Chagas. · Torrico, F., Gascón, J., Ortiz, L., et al. (2018). Treatment of adult chronic indeterminate Chagas disease with benznidazole and three E1224 dosing regimens. The Lancet Infectious Diseases, 18(4), 419–430.

Contribution: criterion of 2 reactive techniques with different principles to confirm Chagas disease.

European Association for the Study of the Liver (EASL). (2017). EASL Clinical Practice Guidelines on the management of hepatitis B virus infection. Journal of Hepatology, 67(2), 370–398. · EASL Recommendations on Treatment of Hepatitis C (2020 update).

Contribution: mandatory neonatal immunoprophylaxis and viral load threshold (>200,000 IU/mL) to add tenofovir in hepatitis B; confirmation with HCV RNA in hepatitis C.

Centers for Disease Control and Prevention (CDC); Organización Panamericana de la Salud (OPS); American College of Obstetricians and Gynecologists (ACOG). Recomendaciones conjuntas de cribado de rubéola en el embarazo.

Contribution: interpretation of rubella IgG/IgM.

Ministerio de Salud Pública y Bienestar Social (MSPBS) / Sociedad Paraguaya de Ginecología y Obstetricia (SPGO). (2018). Manual Nacional de Normas de Atención de las Principales Patologías Obstétricas, chapter 5: Intrahepatic cholestasis of pregnancy (pp. 39–44). Asunción. https://www.mspbs.gov.py/dependencias/progsalud/adjunto/717658-ManualNacionaldeNormasdeAtenciondelasPrincipalesPatologiasObstetricas.pdf

Contribution: national criterion for the ICP card: low risk (bile acids 10–19, normal enzymes; delivery 36–37 wk), moderate (20–39 and/or enzymes up to 2×; admission ≥28 wk) and high (≥40 and/or enzymes >2× or no response; delivery from 36 wk). UDCA 10–16 mg/kg/day and follow-up.

Ministerio de Salud de Chile (MINSAL). (2015). Guía Perinatal, capítulo 11: Colestasia intrahepática del embarazo.

Contribution: regional classification as icteric (bilirubin >1.2 + raised liver enzymes) vs. anicteric, and their respective GA for delivery (36 vs. 38 weeks).

Girling J, Knight CL, Chappell L; Royal College of Obstetricians and Gynaecologists (RCOG). (2022). Intrahepatic cholestasis of pregnancy: Green-top Guideline No. 43. BJOG 2022;129(13):e95-e114. doi:10.1111/1471-0528.17206

Contribution: diagnosis with bile acids ≥19 µmol/L; mild 19–39, moderate 40–99 (birth at 38–39 wk) and severe ≥100 (birth at 35–36 wk).

Society for Maternal-Fetal Medicine (SMFM). Lee, R. H., Mara Greenberg, M., Metz, T. D., & Pettker, C. M. (2021). SMFM Consult Series No. 53: Intrahepatic cholestasis of pregnancy. American Journal of Obstetrics and Gynecology, 224(2), B2–B9.

Contribution: diagnostic and biochemical follow-up framework for ICP current in the USA.

Williamson, C., & Geenes, V. (2014/actualización 2018). Intrahepatic cholestasis of pregnancy. Obstetrics & Gynecology, 124(1), 120–133. · Williamson, C., Mackillop, L., Ovadia, C., et al. (2018). The Lancet, 391, 1683–1696.

Contribution: risk of intrauterine fetal death associated with raised bile acids — rationale for elective delivery in ICP.

Ovadia, C., Seed, P. T., Sklavounos, A., et al. (2019). Association of adverse perinatal outcomes of intrahepatic cholestasis of pregnancy with biochemical markers: results of aggregate and individual patient data meta-analyses. The Lancet, 393(10174), 899–909.

Contribution: meta-analysis quantifying perinatal risk by bile acid level — the reference with the greatest statistical weight for ICP management in the Calculator.

Gomes, A. G. (2001). Altura uterina: análisis de un indicador clínico para el seguimiento del crecimiento fetal. Revista Brasileira de Ginecologia e Obstetrícia, 23(2). · CLAP-OPS/OMS. Curvas de altura uterina.

Contribution: P10/P50/P90 percentiles of fundal height by GA (McDonald technique), valid 20–36 weeks.

Robson, M. S. (2001). Classification of caesarean sections. Fetal and Maternal Medicine Review, 12(1), 23–39.

Contribution: Robson classification by groups (e.g. Group 5: previous caesarean + cephalic) used to contextualise the mode-of-delivery prognosis.

Organización Panamericana de la Salud / Organización Mundial de la Salud. (2018). La clasificación de Robson: manual de aplicación. paho.org

Contribution: 6 variables and 10 groups with subgroups 2a/2b, 4a/4b and 5.1/5.2, used for the "probable group" of the mode-of-delivery card.

Barnea, E. R., et al. (2025). FIGO good practice recommendations for vaginal birth after cesarean. International Journal of Gynecology & Obstetrics, 171(1), 17–31. PMC12447697

Contribution: planning line for groups 5.1 and 5.2 (VBAC with one caesarean, counselling with two, caesarean with three or more; misoprostol contraindicated).

American College of Obstetricians and Gynecologists. (2018, reafirmado 2023). Committee Opinion No. 745: Mode of term singleton breech delivery. PubMed 30045211 · NICE NG137 (2019). Twin and triplet pregnancy. NCBI Bookshelf

Contribution: planning line for groups 6/7 (external cephalic version) and 8 (multiple pregnancy).

Grobman, W. A., Lai, Y., Landon, M. B., et al. — Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Maternal-Fetal Medicine Units Network. (2007). Development of a nomogram for prediction of vaginal birth after cesarean delivery. Obstetrics & Gynecology, 109(4), 806–812. · American College of Obstetricians and Gynecologists (ACOG). Practice Bulletin No. 205: Vaginal Birth After Cesarean Delivery.

Contribution: Grobman score for predicting success of vaginal birth after caesarean (VBAC) — type of scar, previous indication, previous vaginal birth, etc.

Ministerio de Salud Pública y Bienestar Social (MSPBS), Paraguay. Manual Nacional de Normas de Atención de las Principales Patologías Obstétricas. MSPBS · Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG). C-Obs 38: Planned vaginal birth after caesarean section. RANZCOG · Royal College of Obstetricians and Gynaecologists (RCOG). Green-top Guideline No. 45: Birth after previous caesarean birth. RCOG

Contribution: repeat caesarean with 2 or more caesareans (vaginal birth discouraged; if she arrives in the second stage, manage as one previous caesarean). RANZCOG and RCOG: vaginal birth after 2 caesareans with counselling.

Bishop, E. H. (1964). Pelvic scoring for elective induction. Obstetrics & Gynecology, 24, 266–268.

Contribution: items and scores of the Bishop score (dilation, effacement, station, consistency, cervical position; 0 to 13). The original work proposes induction with 9 or more, studied only in multiparous women.

American College of Obstetricians and Gynecologists (ACOG). (2025). Clinical Practice Guideline No. 9: Cervical ripening in pregnancy. Obstetrics & Gynecology, 146(1), 148–160. doi:10.1097/AOG.0000000000005951. acog.org

Contribution: replaces Practice Bulletin 107 (2009). There is no universal definition of an unfavorable cervix: studies used Bishop cutoffs of 3 to 8. Pharmacologic, mechanical or combined ripening methods.

Laughon, S. K., Zhang, J., Troendle, J., Sun, L., & Reddy, U. M. (2011). Using a simplified Bishop score to predict vaginal delivery. Obstetrics & Gynecology, 117(4), 805–811. PMC3297470

Contribution: Simplified Bishop (dilation, effacement, station; 0 to 9): more than 5 predicts vaginal delivery as well as a full Bishop of more than 8.

National Institute for Health and Care Excellence (NICE). (2021). Inducing labour (NG207). nice.org.uk/guidance/ng207

Contribution: Bishop 6 or less: cervical ripening (dinoprostone, oral misoprostol 25 µg or mechanical method); more than 6: amniotomy and oxytocin. Basis of the intermediate zone 7–8.

Wormer, K. C., Bauer, A., & Williford, A. E. (2024). Bishop Score. En StatPearls. StatPearls Publishing. NCBI Bookshelf NBK470368

Contribution: simplified Bishop (dilation, effacement and station; more than 5 favourable) and CMQCC ripening targets (6 or more in multiparous, 8 or more in nulliparous women).

American College of Obstetricians and Gynecologists (ACOG). (2020). Practice Bulletin No. 216: Macrosomia. Obstetrics & Gynecology, 135(1), e18–e35.

Contribution: criteria for preventive planned caesarean for macrosomia (EFW ≥5,000 g in non-diabetic, ≥4,500 g in diabetic women).

Tektonidou, M. G., Andreoli, L., Limper, M., et al. (2019). EULAR recommendations for the management of antiphospholipid syndrome in adults. Annals of the Rheumatic Diseases, 78(10), 1296–1304. PMID 31092409

Contribution: management of the "Antiphospholipid syndrome" finding: aspirin (EULAR indicates 75–100 mg/day; CaVeSal uses the FIGO 2019 dose of ~150 mg) + prophylactic heparin in obstetric APS, therapeutic heparin in thrombotic APS, switch from vitamin K antagonists to heparin before week 6, 6 weeks of postpartum heparin and options for recurrent complications.

Cases 1 to 3: IADPSG 2010, Poon et al. FIGO 2019 and ACOG Practice Bulletin No. 222 (2020), already cited in sections 2 and 3.

Contribution: one source per case: gestational diabetes, preeclampsia screening and prevention, gestational hypertension and preeclampsia.

FIGO Working Group on Best Practice in Maternal–Fetal Medicine. (2015). Best practice in maternal–fetal medicine. International Journal of Gynecology & Obstetrics, 128(1), 80–82.

Contribution: longitudinal case "From first-trimester screening to FGR": variant mentioned in the feedback (low risk <1 in 2500). The case is solved with the Fetal Medicine Barcelona cut-offs (low <1/1100) and also cites Nicolaides 2005, both in section 1.

Medicina Fetal Barcelona (BCNatal). Protocolo: Fetal growth disorders (alteraciones del crecimiento fetal). fetalmedicinebarcelona.org

Contribution: longitudinal case "From first-trimester screening to FGR": SGA/FGR definitions, stages I–IV, follow-up, timing and mode of delivery, lung maturation, neuroprotection with magnesium sulfate and induction method.

World Health Organization. (2024). Guideline on haemoglobin cutoffs to define anaemia in individuals and populations. Geneva: WHO. https://www.who.int/publications/i/item/9789240088542

Contribution: haemoglobin thresholds in pregnancy by trimester (1T <11 · 2T <10.5 · 3T <11 g/dL) and mild/moderate/severe grading — criterion used by the Calculator.

Ubom AE, Begum F, Ramasauskaite D, et al.; FIGO Committee on Childbirth and Postpartum Hemorrhage. (2025). FIGO good practice recommendations on anemia in pregnancy, to reduce the incidence and impact of postpartum hemorrhage (PPH). Int J Gynecol Obstet, 171(3), 993–1007. doi:10.1002/ijgo.70529. https://pmc.ncbi.nlm.nih.gov/articles/PMC12640178/

Contribution: complementary reference: FIGO proposes <11 g/dL in all trimesters. Mentioned in the guide; the Calculator uses WHO 2024.

American College of Obstetricians and Gynecologists. (2021). Anemia in pregnancy: ACOG Practice Bulletin No. 233. Obstet Gynecol, 138(2), e55–e64. doi:10.1097/AOG.0000000000004477

Contribution: ferritin <30 µg/L as the iron-deficiency threshold in pregnancy.

World Health Organization. (2020). WHO guideline on use of ferritin concentrations to assess iron status in individuals and populations. Geneva: WHO. https://www.who.int/publications/i/item/9789240000124

Contribution: ferritin <15 µg/L = depleted iron stores.

Bauer ME, Arendt K, Beilin Y, et al. (2021). The Society for Obstetric Anesthesia and Perinatology interdisciplinary consensus statement on neuraxial procedures in obstetric patients with thrombocytopenia. Anesth Analg, 132(6), 1531–1544. doi:10.1213/ANE.0000000000005355

Contribution: neuraxial anaesthesia with platelets ≥70 ×10³/µL if there is no other coagulopathy.

Abbassi-Ghanavati M, Greer LG, Cunningham FG. (2009). Pregnancy and laboratory studies: a reference table for clinicians. Obstet Gynecol, 114(6), 1326–1331. doi:10.1097/AOG.0b013e3181c2bde8

Contribution: trimester ranges for uric acid (upper limit 4.2 / 4.9 / 6.3 mg/dL) and urea (BUN 3–13 mg/dL).

Wiles K, Bramham K, Seed PT, Nelson-Piercy C, Lightstone L, Chappell LC. (2018). Serum creatinine in pregnancy: a systematic review. Kidney Int Rep, 4(3), 408–419. doi:10.1016/j.ekir.2018.10.015. https://pmc.ncbi.nlm.nih.gov/articles/PMC6409397/

Contribution: creatinine >0.87 mg/dL (77 µmol/L) outside the normal range of pregnancy.

American College of Obstetricians and Gynecologists. (2020). Gestational hypertension and preeclampsia: ACOG Practice Bulletin No. 222. Obstet Gynecol, 135(6), e237–e260.

Contribution: creatinine >1.1 mg/dL (or doubling) as a preeclampsia severity criterion.

Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. (2011). Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab, 96(7), 1911–1930. doi:10.1210/jc.2011-0385

Contribution: origin of the range laboratories use for 25(OH)D: deficiency <20, insufficiency 20–29, sufficiency ≥30 ng/mL.

World Health Organization. (2020). WHO antenatal care recommendations for a positive pregnancy experience. Nutritional interventions update: vitamin D supplements during pregnancy. Geneva: WHO. https://www.who.int/publications/i/item/9789240008120

Contribution: vitamin D supplementation is not recommended for all pregnant women; supplement when deficiency is documented or suspected.

Demay MB, Pittas AG, Bikle DD, et al. (2024). Vitamin D for the prevention of disease: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab, 109(8), 1907–1947. doi:10.1210/clinem/dgae290

Contribution: does not recommend routine 25(OH)D testing in pregnancy and suggests empirical supplementation.

Lazarus JH, Bestwick JP, Channon S, et al. (2012). Antenatal thyroid screening and childhood cognitive function. N Engl J Med, 366(6), 493–501. doi:10.1056/NEJMoa1106104

Contribution: CATS trial: 21,846 women; treating subclinical hypothyroidism or hypothyroxinemia from ~13 weeks did not improve child IQ at 3 years (99.2 vs 100.0).

Casey BM, Thom EA, Peaceman AM, et al.; NICHD MFMU Network. (2017). Treatment of subclinical hypothyroidism or hypothyroxinemia in pregnancy. N Engl J Med, 376(9), 815–825. doi:10.1056/NEJMoa1606205

Contribution: TSH ≥4.0 treated from ~17 weeks: no difference in IQ at 5 years (97 vs 94). With CATS, the basis for stating that the high TSH–neurodevelopment link is observational.

Ross AC, Manson JE, Abrams SA, et al. (2011). The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metab, 96(1), 53–58. doi:10.1210/jc.2010-2704

Contribution: IOM criterion: 25(OH)D <12 ng/mL at risk of deficiency, 12–19 possibly inadequate, ≥20 sufficient for bone health; recommended intake 600 IU/day.

Bouillon R. (2017). Comparative analysis of nutritional guidelines for vitamin D. Nat Rev Endocrinol, 13(8), 466–479. doi:10.1038/nrendo.2017.31

Contribution: comparison of 25(OH)D cutoffs across societies (IOM, Endocrine Society, SACN and others); shows there is no single threshold.

Federación Latinoamericana de Sociedades de Obstetricia y Ginecología (FLASOG). (2026). Recomendaciones sobre vitamina D en salud reproductiva. Ginecol Obstet Mex, 94, e11309.

Contribution: pregnancy dose 1000–2000 IU/day, maximum 4000 IU/day.