First-trimester crown-rump length as a predictor of fetal LGA and SGA at term

Abstract

OBJECTIVE: To determine whether first-trimester crown-rump length (CRL) is associated with birthweight extremes at term. METHODS: Included in this study were all term, small for gestational age (SGA), and large for gestational age (LGA) neonates with no other obstetric complications and no abnormal outcomes of pregnancy. CRL at 12.0 to 12.6 weeks of estimated gestational age obtained during nuchal translucency screening was selected as an estimate of early fetal growth. Mean first-trimester CRL of the LGA noenates at term was compared via student's t-test with mean first-trimester CRL of SGA neonates at term. RESULTS: In all, 121 neonates were included in the study. Mean first-trimester CRL of the 63 LGA-term neonates was 62.7 ± 6.0 mm (95% confidence interval, ± 1.49 mm; range, 61.21-64.19), while that of the 58 SGA-term neonates was smaller at 58.8 ± 6.9 mm (95% confidence interval, ± 1.79 mm; range, 57.01-60.59 mm). This 3.9 mm difference between the means was statistically significant (P = 0.01). CONCLUSION: We found that birthweights of LGA and SGA neonates at term were associated with their first-trimester CRL measurements, thus, indicating that fetal growth patterns apparent early in pregnancy continue through term.