Birth weight differences at term are explained by placental dysfunction, but not by maternal ethnicity

Abstract

OBJECTIVE: The main aim of this study was to investigate the influence of ethnicity, fetal gender and placental dysfunction on birth weight (BW) in term fetuses of South Asian and Caucasian origin. METHODS: This was a retrospective study of 627 term pregnancies assessed in two public tertiary hospitals in Spain and Sri Lanka. All fetuses underwent a scan and Doppler examination within two weeks of delivery. The influences of fetal gender, ethnicity, gestational age (GA) at delivery, cerebroplacental ratio (CPR), maternal age, height, weight and parity on BW were evaluated by multivariable regression analysis. RESULTS: Fetuses born in Sri Lanka were smaller than those born in Spain (mean BW= 3026g±449g versus 3295g±444g, p<0.001). Multivariable regression analysis demonstrated that GA at delivery, maternal weight, CPR, maternal height and fetal gender (estimates=0.168, p<0.001; 0.006, p<0.001; 0.092, p=0.003; 0.009, p=0.002; 0.081, p=0.01) were significantly associated with BW. Conversely, no significant association was noted with maternal ethnicity, age and parity (estimates= -0.010, p=0.831; 0.005, p=0.127; 0.035, p=0.086). The findings were unchanged when the analysis was repeated using IG21 EFW instead of BW centile (-0.175, p=0.170; 0.321, p<0.001). CONCLUSIONS: Fetal BW variation at term is less dependent on ethnic origin and better explained by placental dysfunction.