Grain consumption before and during pregnancy and birth weight in Japan: the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study

Background/objectives Studies have reported the effects of grain consumption on human health, but the association between maternal grain consumption before and during pregnancy and birth weight remains unclear. We evaluated the association between maternal grain consumption before and during pregnancy and birth weight/low birth weight (LBW). Subjects/methods Grain consumption was calculated using two semi-quantitative food frequency questionnaires (FFQs). The two FFQs evaluated consumption from pre- to early pregnancy and then from early to mid-pregnancy, respectively. Information concerning birth weight was obtained from birth records, and multivariable analyses for birth weight and LBW risk were conducted after adjusting for potential confounders. Results In total, 17,610 pregnant women (age, 31.8 ± 4.9 years; smoked during pregnancy, 16.1%; gestation period, 38.5 ± 2.5 weeks; first childbirth, 45.5%) and their singleton and term new-borns (birth weight, 3061.8 ± 354.1 g; LBW, 5.4%) were included in the analysis. Women in the highest quartile of grain consumption from pre- to early pregnancy had heavier new-borns (β = 22.3; 95% confidence interval (CI): 5.8-38.9) but did not have a significantly lower LBW risk (odds ratio [OR]: 0.87; 95% CI: 0.71-1.07) than women in the lowest quartile. Women in the highest quartile of grain consumption from early to mid-pregnancy also had heavier new-borns (β = 24.1; 95% CI: 7.1-41.1) but did not have a significantly lower LBW risk (OR: 0.85; 95% CI: 0.69-1.05) than women in the lowest quartile. Conclusions Grain consumption before and during pregnancy was positively associated with birth weight.