Unisex versus sex-specific estimated fetal weight charts for fetal growth monitoring: a population-based study.

Abstract Background In contrast with birthweight or other growth charts, a feature of most intrauterine charts is that they are not differentiated by sex. Differences in weight by sex during pregnancy are considered to be relatively minor, however, small systematic differences may affect the sensitivity and specificity of screening for fetuses with growth restriction. Objective To assess differences between unisex and sex-specific estimated fetal weight (EFW) charts at the third trimester ultrasound on the sex ratio of fetuses detected with an EFW Study design The study included 9940 singleton live births from a French population-based study in 2016. Main outcomes were an EFW Results Among all singleton births, there were 51.6% males and 48.4% females. Males faced higher risks of SGA with morbidity at birth (2.4% vs 1.8%, P=.031). Using the WHO unisex chart, 6.9% of males and 9.9% of females had an EFW Conclusion This study suggests that use of sex-specific charts instead of unisex charts would avert sex-bias in intrauterine growth screening during the third trimester of pregnancy. Prospective studies are needed to assess the effects of using sex-specific charts compared to unisex charts on obstetrical management and outcomes.