Maternal and paternal early-pregnancy dietary glycemic index, embryonic development and adverse birth outcomes

Background & Aims: We examined associations of parental early-pregnancy dietary glycemic index (GI) with embryonic growth and yolk sac development, and their subsequent associations with fetal growth and adverse birth outcomes.Methods: Among 778 women and 602 partners participating in a population-based prospective cohort study from preconception onwards, we assessed dietary intake GI by FFQ at median 12.4 weeks gestation. Crown-rump length (CRL) and yolk sac volume were assessed by 7, 9, and 11 weeks ultrasounds. Information on birth outcomes was obtained from medical records.Results: Compared to the highest maternal GI quartile, the lowest maternal GI quartile was associated with larger embryonic growth from 7 to 11 weeks gestation, but differences in growth decreased from 30 weeks gestation onwards, tending to result in a smaller size at birth (CRL differences: 0.23 SDS, 95% CI 0.01, 0.44; 0.21 SDS, 95% CI 0.01, 0.41; 0.19 SDS, 95% CI 0.00, 0.38, at 7, 9, 11 weeks gestation, respectively). The third paternal GI quartile was associated with a larger embryonic CRL at 9 and 11 weeks gestation compared to the highest paternal GI quartile (p-values <0.05). No effects across the full range of parental GI with embryonic growth were present. No consistent associations were observed between parental GI and yolk sac volume or adverse birth outcomes.Conclusion: A low maternal early-pregnancy dietary GI and moderate paternal dietary GI are associated with larger embryonic growth, but not with yolk sac development, throughout the first trimester. No subsequent differences in fetal growth or adverse birth outcomes were present.