Comparison of fetal growth patterns from Western India with Intergrowth-21st

To generate longitudinal fetal growth data in an Indian population and compare it with Intergrowth-21st.

Fetal biometry data was collected in a prospective longitudinal observational study (REVAMP: Research Exploring Various Aspects and Mechanisms in Preeclampsia) from 2017 to 2022. Fetal crown-rump length (CRL) was measured at 11-14 weeks gestation, and biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL) at 18-22 and 32-35 weeks, and converted into Z-scores using the Intergrowth standard. Generalized Additive Models for Location, Scale and Shape (GAMLSS) models were used to construct fetal growth centile curves compared against Intergrowth centiles.

Out of 1096 singleton pregnancies in REVAMP, this analysis included 655 'healthy' pregnancies (uncomplicated by pre-eclampsia, diabetes, pre-term delivery or low birth weight) and a sub-set of 106 'low-risk' pregnancies defined using Intergrowth criteria. The 'healthy' study subjects showed lower mean CRL Z-score [-0.45 SD (95% CI:-0.54,-0.37)] at 11-14 weeks, and BPD Z-score [-1.2 SD (-1.28,-1.11) and -1.17 SD (-1.23,-1.1)] at 18-22 and 32-35 weeks respectively. Mean HC Z-score was comparable to the Intergrowth standard at 18-22 weeks [-0.08 SD (-0.16, 0.02)] but smaller at 32-35 weeks [-0.25 SD (-0.32,-0.19)]. Mean AC Z-score was lower at 18-22 weeks [-0.32 SD (-0.41,-0.23)] but comparable at 32-35 weeks [0.004 SD (-0.07, 0.07)]. FL was comparable to or larger than the Intergrowth standard at both time points [0.05 SD (-0.05, 0.14); 0.82 SD (0.75, 0.89), respectively]. These findings were similar, though measurements were slightly larger, in the 'low-risk' sample.

This data from healthy and low-risk pregnant women in urban western India indicates that some fetal dimensions and growth trajectories differ significantly from the Intergrowth-21st. Our data suggest the need for a larger representative study to define a population-specific fetal growth reference for India, for identification of fetal growth restriction.