De uitgerekende datum

Geschreven door Lisette Nijenhuis, Annemieke Verbeek
Gepubliceerd op: 12 april 2024
Laatste update op: 20 december 2024

Het is een van de eerste vragen die elke zwangere krijgt: wanneer ben je uitgerekend? Die datum staat niet alleen omcirkeld in de agenda van de meeste toekomstige ouders, het is ook bepalend voor beleid rondom de bevalling (denk aan inleiden bij ‘over tijd’ gaan) – en daarom meer dan alleen een geinig weetje.

In Nederland is het sinds 2010 standaard om tussen de 10-13 weken zwangerschap een termijnecho aan te bieden om de uitgerekende datum te bepalen. Daarvoor was de zogeheten Regel van Nagaele leidend – waarbij er een rekensommetje vanaf de eerste dag van de laatste menstruatie de uitgerekende datum bepaalde.

De uitgerekende datum is gebaseerd op de aanname dat een zwangerschap veertig weken duurt (bij een vitale eenling). De uitgerekende datum is de ‘mediaan’, 50% van de vrouwen bevalt ervoor en 50% erna (dit is niet hetzelfde als het gemiddelde, hierover later meer). Slechts 5% van de zwangeren bevalt precies op de uitgerekende datum.

Kloppen die 40 weken eigenlijk wel? En hoe betrouwbaar is het vaststellen van de uitgerekende datum op basis van een echo? Daarover gaat dit artikel. Ook kijken we naar de voor- en nadelen van het hebben van een uitgerekende datum.

American Society for Reproductive Medicine, 2021, Diagnosis and treatment of luteal phase deficiency: A committee opinion. Fertility and Sterility, https://doi.org/10.1016/j.fertnstert.2021.02.010

Baskett, T., 2005, Naegele's rule: a reappraisal, https://pubmed.ncbi.nlm.nih.gov/11117775/

Blaas, H. et al, 1998, The growth of the human embryo. A longitudinal biometric assessment from 7 to 12 weeks of gestation, https://pubmed.ncbi.nlm.nih.gov/9819874

Bergsjø, P. et al., 1990, Duration of human singleton pregnancy: a population-based study, https://doi.org/10.3109/00016349009028681.

Baskett, T. F., & Nagele, F. (2000). Naegele’s rule: a reappraisal. BJOG: An International Journal of Obstetrics and Gynaecology, https://doi.org/10.1111/j.1471-0528.2000.tb11661.x.

Buck Luis, G. et al, 2016, Racial/Ethnic Standards for Fetal Growth, the NICHD Fetal Growth Studies, https://pmc.ncbi.nlm.nih.gov/articles/PMC4584427/

Caughey, A.et al., 2009, Who is at risk for prolonged and postterm pregnancy? https://doi.org/10.1016/j.ajog.2009.02.034.

Dekker, R. (geraadpleegd op 9 juli 2023, 9 juli), Evidence on: Due dates - Evidence based birth®. Evidence Based Birth®. https://evidencebasedbirth.com/evidence-on-due-dates/.

Divon, M. et al., 1998, Fetal and neonatal mortality in the postterm pregnancy: The impact of gestational age and fetal growth restriction, https://doi.org/10.1016/s0002-9378(98)70482-x.

Doubilet, P. 2013, Should a first trimester dating scan be routine for all pregnancies?, https://www.sciencedirect.com/science/article/abs/pii/S0146000513000712?via%3Dihub

Jakubowski, D. et al, 2020, The crown-rump length measurement - ISUOG criteria and clinical practice, https://pubmed.ncbi.nlm.nih.gov/33301161/

Jukic, A. et al., 2013, Length of human pregnancy and contributors to its natural variation, https://doi.org/10.1093/humrep/det297.

Kagan, K. et al., 2012, Impact of bias in crown–rump length measurement at first‐trimester screening for trisomy 21, https://doi.org/10.1002/uog.11095.

Khambalia, A., et al., 2013, Predicting date of birth and examining the best time to date a pregnancy, https://doi.org/10.1016/j.ijgo.2013.05.007.

Lawson, G., 2020, Naegele’s Rule and the length of pregnancy – a review, https://doi.org/10.1111/ajo.13253

Loytved, C. et al., 2016, Naegele’s rule revisited, https://doi.org/10.1016/j.srhc.2016.01.005.

Mahendru, A. et al., 2012, Impact of ovulation and implantation timing on first-trimester crown-rump length and gestational age, https://doi.org/10.1002/uog.12277

Mittendorf, R. et al., 1993, Predictors of human gestational length, https://doi.org/10.1016/0002-9378(93)90476-y

Mongelli, M. et al., 1996, Estimating the date of confinement: Ultrasonographic biometry versus certain menstrual dates, https://doi.org/10.1016/s0002-9378(96)70408-8

Morken, N. et al., 2014, Perinatal mortality by gestational week and size at Birth in Singleton Pregnancies at and Beyond Term: A nationwide population-based cohort study, https://doi.org/10.1186/1471-2393-14-172

National Childbirth Trust (2023, 17 november). Pregnancy Week 1 | Pregnancy, Your Pregnancy Week by Week Articles & Support | NCT. NCT (National Childbirth Trust). https://www.nct.org.uk/pregnancy/your-pregnancy-week-week/first-trimester/pregnancy-week-1#:~:text=In%20France%20pregnancy%20is%20counted,on%20the%20due%20date%20calculated.

NVOG, 2018, Protocol datering van de zwangerschap

Olesen, A. et al., 2003, Risk of recurrence of prolonged pregnancy, https://doi.org/10.1136/bmj.326.7387.476

Öberg, S. et al., 2013, Maternal and Fetal genetics contributions to Postterm birth: familial clustering in a Population-Based sample of 475,429 Swedish births, https://doi.org/10.1093/aje/kws244

Papiernik, E. et al., 1990, Racial differences in pregnancy duration and its implications for perinatal care, https://doi.org/10.1016/0306-9877(90)90173-c.

Patel, R.,2004, Does gestation vary by ethnic group? A London-based study of over 122 000 pregnancies with spontaneous onset of labour, https://doi.org/10.1093/ije/dyg238.

Perinatol, A., 1994, Accurate gestational dating: revisited, https://pubmed.ncbi.nlm.nih.gov/7857430/

Robinson, H., 1975, a critical evaluation of sonar “crown-rump length” measurements, https://doi.org/10.1111/j.1471-0528.1975.tb00710.x

Smith, G., 2001,. Use of time to event analysis to estimate the normal duration of human pregnancy, https://doi.org/10.1093/humrep/16.7.1497.

Sahota, D. et al, 2009, Fetal crown-rump length and estimation of gestational age in an ethnic Chinese population, https://pubmed.ncbi.nlm.nih.gov/19115262/

Stotland, N. et al., 2007, Prepregnancy body mass index and the length of gestation at term, https://doi.org/10.1016/j.ajog.2007.05.048

Su, H. et al., 2017, Detection of ovulation, A review of currently available methods, https://doi.org/10.1002/btm2.10058

Taipale, P. et al., 2001, Predicting delivery date by ultrasound and last menstrual period in early gestation, https://doi.org/10.1016/s0029-7844(00)01131-5.

Treloar, A. et al., 1967, Analysis of gestational interval, https://doi.org/10.1016/s0002-9378(16)34488-x.

Tuck, S. et al., 1983, Obstetric characteristics in different racial groups, https://doi.org/10.1111/j.1471-0528.1983.tb06759.x

Weiß, G. et al., 2022, Confirmation of human ovulation in assisted reproduction using an adhesive axillary thermometer (FEMSense®), https://doi.org/10.3389/fdgth.2022.930010

Whitworth, M. et al., 2015, Ultrasound for fetal assessment in early pregnancy. The Cochrane library, https://doi.org/10.1002/14651858.cd007058.pub3

Wilcox, M. et al., 1993, Birth weight from pregnancies dated by ultrasonography in a multicultural British population, https://doi.org/10.1136/bmj.307.6904.588