Maternal Weight Gain in Early Pregnancy with Healthy Live Offspring: Based on the China Birth Cohort Study

Research on maternal weight gain in early pregnancy with healthy live offspring is lacking for Chinese women. Based on the China birth cohort study (CBCS), we aimed to explore maternal weight gain in different groups.

Singleton pregnancies of 6 ^{+ 0}~13 ^{+ 6} weeks of gestation from the CBCS were considered, not including missing data or outliers, those lost at follow-up, or those with non-typical conditions of the offspring. Maternal first-trimester weight and body mass index (BMI) gain was considered as the early pregnancy weight minus the pre-pregnancy weight. Using Pearson's or Spearman's correlation and linear regression models to explore the relationship between maternal weight and BMI gain and gestational age (GA), stratified and sensitivity analyses were carried out to identify the study's robustness.

There were 25,292 singleton pregnancies with healthy live offspring who were ultimately enrolled, and there was a linear correlation between GA and maternal weight gain (=0.55 + 0.05 × GA (weeks), p < 0.001, r² = 0.002) and BMI change (=0.21 + 0.02 × GA (weeks), p < 0.001, r² = 0.002). The association remained robust in the stratified and sensitivity analyses of the subgroups.

Although the association between GA and maternal pre-pregnancy weight and BMI gain is weak, a slight correlation was shown, especially in pregnant women with a typical or low pre-pregnancy BMI, Han ethnicity, moderate levels of physical activity, natural conception, and folic acid (FA) and/or multivitamin supplementation.