Correlation of first‐trimester fetal crown–rump length with outcome of pregnancy and birth weight

Abstract

OBJECTIVE: To examine the association of crown-rump length (CRL) in the first trimester with low birth weight and adverse pregnancy outcome. METHODS: In a prospective cross-sectional study, CRL was measured in 876 healthy pregnant women undergoing ultrasound evaluation between 9 and 14 weeks of gestation. Birth weight and pregnancy outcomes were analyzed for the 544 participants who met the study criteria. RESULTS: Low (<2500 g) and high (>4000 g) birth weights were correlated with the difference between actual and expected CRL expressed in days of gestation, but no correlation was found between the difference between actual and expected CRL and premature delivery. Low birth weight (P=0.005) and abortion (P=0.03) were also correlated with the difference between actual and expected CRL. CONCLUSION: Routinely measuring CRL during the first trimester to detect CRLs shorter than expected for gestational age could be useful to obstetricians. Anticipating a low birth weight and being warned about the possibility of abortion would enable them to manage prenatal care and delivery more appropriately.