Association Between Gestational Weight Gain and Delayed Onset of Lactogenesis II: a Systematic Review and Meta-Analysis.

Background: Gestational weight gain (GWG) may be associated with delayed onset of lactogenesis II (DOL II), but it is still unclear and controversial. Object: The study aims to evaluate the relationship between GWG and DOL II. Methods: A comprehensive search was performed in 10 electronic databases from inception to May 21, 2023, for studies that reported outcomes in breastfeeding. Data were extracted by two independent reviewers. A meta-analysis was conducted to calculate the pooled estimates of association using random-effect models with Review Manager (RevMan) software version 5.4. The primary outcome was the rate of DOL II. Results: In this study, 248,515 women were included in 16 eligible articles. Women with excessive GWG have a higher risk of DOL II (odds ratio [OR] = 1.28; 95% confidence interval [CI]: 1.15-1.43). Specifically, prepregnancy overweight and obese women with GWG above recommendations (OR = 3.01, 95% CI: 1.38-6.57) and underweight women with excessive GWG before pregnancy have a higher risk of DOL II (OR = 3.32, 95% CI: 1.69-6.53). Nonetheless, there is no distinction between women with inadequate GWG and those with adequate GWG in DOL II(OR = 1.08, 95% CI: 0.88-1.33). In addition, the women whose GWG is above the recommendations also tend to stop exclusive breastfeeding 1 month postpartum (OR = 0.82, 95% CI: 0.80-0.85). Conclusion: Excessive GWG has a negative influence on the timing of the onset of lactogenesis and exclusive breastfeeding within 1 month postpartum.