RESUMO
OBJECTIVES: Little study has reported the association of maternal weight gain in early pregnancy with fetal congenital heart disease (CHD). We aimed to explore the potential relationship based on a China birth cohort while adjusting by multiple factors. DESIGN: Cohort study. SETTING: China birth cohort study conducted from 2017 to 2021. PARTICIPANTS: The study finally included 114 672 singleton pregnancies in the 6-14 weeks of gestation, without missing data or outliers, loss to follow-up or abnormal conditions other than CHD. The proportion of CHD was 0.65% (749 cases). PRIMARY AND SECONDARY OUTCOME MEASURES: Association between maternal pre-pregnancy weight gain and CHD in the offspring were analysed by multivariate logistic regression, with the unadjusted, minimally adjusted and maximally adjusted methods, respectively. RESULTS: The first-trimester weight gain showed similar discrimination of fetal CHD to that period of maternal body mass index (BMI) change (DeLong tests: p=0.091). Compared with weight gain in the lowest quartile (the weight gain less than 0.0 kg), the highest quartile (over 2.0 kg) was associated with a higher risk of fetal CHD in unadjusted (OR 1.36, 95% CI: 1.08 to 1.72), minimally adjusted (adjusted OR (aOR) 1.29, 95% CI: 1.02 to 1.62) and maximally adjusted (aOR 1.29, 95% CI: 1.02 to 1.63) models. The association remains robust in pregnant women with morning sickness, normal pre-pregnancy BMI, moderate physical activity, college/university level, natural conception or with folic acid (FA) and/or multivitamin supplementation. CONCLUSIONS AND RELEVANCE: Although the association of maternal pre-pregnancy weight gain on fetal CHD is weak, the excessive weight gain may be a potential predictor of CHD in the offspring, especially in those with morning sickness and other conditions that are routine in the cohort, such as normal pre-pregnancy BMI, moderate physical activity, college/university level, natural conception or with FA and/or multivitamin supplementation.