CORRELATION BETWEEN CROWN RUMP LENGTH MEASURED IN EARLY FIRST TRIMESTER AND BIRTH WEIGHT OF THE RESPECTIVE NEWBORN

M. Samutirika Devi, N. S. Raghupathy, M. Mathivanan and M. Srilakshmi Chordia*

ABSTRACT

Background and Aim: Determination of early fetal growth abnormalities is one of the most important aspects of antenatal healthcare. In this study, we attempted to sonographically assess the correlation of early first trimester (>8 to <11 weeks) crown-rump length (CRL)with birth weight. Method: A prospective observational study with 252 women (19-39 years) having uneventful pregnancies were assessed for CRL during the early first trimester sonographically and followed up till delivery. The birth weight of their respective newborn was categorized into Small for Gestational Age (SGA), Appropriate for Gestational Age (AGA) and Large for Gestational Age (LGA). Both variables were correlated and analysed using SPSS 21.0 software. Analysis of variance (ANOVA), independent ‘t’-test, kappa-coefficient, Pearson bivariate correlation and linear regression were performed. Results: Mean early first-trimester CRL was 26.24±8.41 mm. There was a significant incremental trend of CRL with gestational age. The first-trimester CRL predicted AGA in 203 (80.6%), SGA in 37 (14.7%) and LGA in 12 (4.8%) pregnancies. At delivery, 205 (81.3%) were AGA, 35 (13.9%) were SGA and 12 (4.8%) were LGA. Agreement between estimated and actual growth categories was observed in 228/252 (90.5%) cases. Sensitivity, specificity, PPV, NPV and accuracy of CRL based estimations of birth weight category were 93.7%, 76.6%, 94.6%, 73.5%, 92.1% for AGA, 80%, 95.9%, 75.7%, 95.9%, 93.7% for SGA and 66.7%, 98.3%, 66.7%, 98.3% 96.8% for LGA. Conclusion: The findings of this study suggest that early first-trimester CRL can be used for the prediction of birth weight in uncomplicated pregnancies.

Keywords: Early first-trimester, Crown-rump length, Sonography, birth weight, SGA, AGA, LGA.