Clusters of week-specific maternal gestational weight gain pattern and their association with birthweight: an observational cohort study.

Abstract

Gestational weight gain varies widely among different populations, and an inappropriate gestational weight gain is associated with adverse pregnancy outcomes. We aimed to investigate week-specific serial changes in gestational weight gain in an urban Chinese population to derive clusters of gestational weight gain patterns and explore the impact of gestational weight gain patterns on birthweight. This was an observational cohort study of 6130 women delivered at a university hospital in Shanghai, China. Pre-pregnancy bodyweight, height, week-specific and total gestational weight gain, pregnancy outcome and birthweight were extracted using electronic medical records. The association between gestational weight gain and gestational age was tested using linear regression, and week-specific reference percentiles for gestational weight gain were calculated. Hierarchical clustering was used to derive gestational weight gain clusters. Mean birthweight among the clusters was compared using Dunnet's test. We found a significant linear association between gestational weight gain and gestational age (r=0.56; p<0.00001). Seven distinct clusters of gestational weight gain pattern were identified. The birthweight significantly correlated with gestational weight gain (r=0.28; p<0.00001). Compared with the cluster that had normal gestational weight gain throughout the pregnancy, the mean birthweight among the clusters that had abnormal gestational weight gain (inadequate or excessive) in the third trimester was significantly different (p<0.001), but those who achieved normal gestational weight gain (between 5 and 95 percentile) in the third-trimester had similar mean birthweight. Women with abnormal gestational weight gain before the third-trimester still had a fair chance of delivering a normal birthweight baby if their gestational weight gain was normal in the third-trimester, suggesting that interventions started even late in pregnancy may have a positive effect on fetal growth.