Associations of Gestational Weight Gain Up to 24 Weeks with Pregnancy Outcomes: A Chinese Retrospective Cohort Study.

Background: Although inadequate or excessive gestational weight gain (GWG) has been associated with adverse pregnancy outcomes, most studies in China have applied the Institute of Medicine (IOM) guideline, which may not be optimal for Chinese women. Evidence on early-mid pregnancy weight gain and perinatal outcomes remains limited. Methods: This single-center retrospective cohort study included singleton live births delivered at Shanghai General Hospital between January and December 2021. GWG24 was calculated as measured weight at approximately 24 gestational weeks minus self-reported pre-pregnancy weight and categorized according to the 2022 Chinese GWG guideline. Logistic regression analyses were performed to evaluate associations between GWG24 and pregnancy outcomes. Results: Among 976 women, 122 (12.5%) were below-range, 490 (50.2%) were within-range, and 364 (37.3%) were above-range GWG24. Compared with within-range GWG24, below-range GWG24 was associated with higher odds of small for gestational age (SGA; adjusted OR 3.00, 95% CI 1.46-6.14) and lower odds of large for gestational age (LGA; adjusted OR 0.44, 95% CI 0.23-0.84). Above-range GWG24 was not significantly associated with SGA or LGA. Maternal outcomes included GDM, gestational hypertension, preeclampsia, caesarean delivery, and PPH; neonatal outcomes included SGA, LGA, macrosomia, and low birthweight. Conclusion: Below-range GWG24, classified according to the 2022 Chinese guideline, was associated with higher odds of SGA and lower odds of LGA. GWG24 may help identify women at increased risk of adverse fetal growth outcomes.