Expected day of delivery from ultrasound dating versus last menstrual period—obstetric outcome when dates mismatch

Abstract

Objective To analyse the association between fetal size at time of dating ultrasound and risk for preterm delivery and small‐for‐gestational‐age (SGA) birth and to evaluate if timing of ultrasound, that is before 14 weeks of gestation or after 16 weeks affects this association. Design Retrospective cohort study. Setting Ultrasound departments of Ultragyn, Stockholm, Sweden. Population A total of 28 776 singleton pregnancies dated between 1998 and 2004. Methods Obstetric outcome was assessed through linkage of the cohort to the Swedish Medical Birth Register. Main outcome measures Risks of preterm delivery, low birthweight for gestational age, pre‐eclampsia, asphyxia, respiratory distress, instrumental delivery, caesarean section, and postterm birth were calculated for the groups dated early and late. Results When the expected date of delivery was postponed after ultrasound dating by 7 days or more, there was an increased risk for preterm delivery and pre‐eclampsia in the late dating group (OR 1.49, 95% CI 1.27–1.73 and OR 1.27, 95% CI 1.02–1.60, respectively) but not in the early dating group. In both dating groups, there was an increased risk for SGA birth (OR 1.77, 95% CI 1.13–2.78 and OR 2.09, 95% CI 1.59–2.73, respectively) There was no increased risk for any of the other diagnoses. Conclusion Our study gives further support to the notion that intrauterine growth restriction may be present as early as the first trimester. Accordingly, our study also suggests that surveillance of pregnancies with postponed estimated date of delivery may provide means for increased detection of fetal growth restriction.

Ultrasound Pregnancy Dating Leads to Biased Perinatal Morbidity and Neonatal Mortality Among Post-term-born Girls

“…16,17 Studies have, however, shown detectable differences in biparietal diameter already at the end of the first trimester with respect to fetal sex, 18 -20 maternal smoking, 21,22 and early growth restriction. 23 Thus, it is plausible that second-trimester ultrasound dating may lead to systematic errors in estimation of gestational age.…”

Survival and neonatal morbidity among extremely preterm born infants in relation to gestational age based on the last menstrual period or ultrasonographic examination

“…Estimation of GA by ultrasonographic biometry is recognized as being more reliable than GA-LMP [9,18,30] mostly because estimation based on the LMP assumes that conception occurs on day 14 of the cycle, whereas the time point of ovulation during the menstrual cycle varies greatly. Indeed, several studies have shown that estimation of GA based on LMP, even when the recall is certain, is unreliable [4,11,28,32].…”

“…Today, it is generally accepted that estimation of GA by ultrasound (US) in early pregnancy is more precise and reliable than dating based on the last menstrual period (LMP) [9,14,18,30], and US fetometry has become the exclusive means of pregnancy dating in Sweden during the past decades [13]. Consequently, if the estimated date of delivery according to the LMP (GA-LMP) and according to US examination (GA-US) differs, obstetricians rely entirely on the latter [1].…”

“…Indeed, a recent Swedish study confirmed that such a discrepancy reflects early intrauterine growth restriction (IUGR), a phenomenon associated with enhanced risk for small for GA (SGA) birth weight, preterm delivery, and preeclampsia [30].…”

Comment déterminer la date de début de grossesse ?

“…Principalement dans des populations issues de PMA, pour lesquelles la DDG est connue, il a été montré qu'une LCC plus petite qu'attendue était associée à un risque majoré de retard de croissance voire de mort foetale in utero et, à l'inverse, qu'une LCC plus grande qu'attendue était associée à un risque accru de macrosomie, de disproportion foeto-pelvienne et de dystocie (NP3) [48][49][50][51][52][53][54][55][56][57][58][59][60][61]. Il n'y a toutefois à ce jour pas de consensus sur la gestion de telles discordances.…”