475 - Is maternal body weight or composition associated with onset of lactogenesis II, human milk production or infant consumption of mother’s milk? A systematic review and meta-analysis
Graduate Student MSc Candidate University of Toronto Temerty Faculty of Medicine Toronto, Ontario, Canada
Background: Maternal weight status may influence onset of lactogenesis II (copious milk), human milk production, and subsequent infant consumption, but the underlying associations between these factors are not well understood. Objective: To explore whether maternal weight status is associated with onset of lactogenesis II (hours), human milk production (pumped volume/24hrs), and infant consumption of mother’s milk (volume/24hrs). Design/Methods: We searched electronic databases (Embase, Medline, Cochrane, CINAHL, Scopus, Web of Science) and the grey literature (May 2023). Standard meta-analyses compared the relative risk (RR) of delayed lactogenesis II (>72 hours) between mothers with underweight (BMI < 18.5kg/m2), healthy weight (BMI 18.6-24.9 kg/m2), and overweight/obesity (BMI >25.0kg/m2). Random-effects meta-regressions examined the association between maternal BMI or percent fat mass, onset of lactogenesis II and infant consumption of mother’s milk. We narratively reviewed studies reporting milk production due to limited data. We assessed the certainty of evidence (Grading of Recommendations, Assessment, Development and Evaluation approach). Results: We reviewed 15,887 abstracts and 319 full articles; 74/122 included articles had data for meta-analysis. Mothers with underweight (RR: 0.64; 95% CI: 0.49, 0.83; I2= 39.48%; n= 8 articles/datapoints) and healthy weight (RR: 0.67, 95% CI: 0.57, 0.79; I2= 70.91%; n= 15 articles/datapoints) were significantly less likely to experience delayed lactogenesis II than mothers with overweight/obesity. However, the linear association between maternal BMI and onset of lactogenesis II was not statistically significant (ß= 1.45 hours; 95% CI: -3.19, 6.09; p= 0.52, I2= 0.00%; 17 datapoints/12 articles). We found no significant associations between maternal BMI (ß= 6.23mL; 95% CI: -11.26, 23.72; p= 0.48, I2= 47.23%; 75 datapoints/54 articles) or percent fat mass (ß= 7.82mL; 95% CI: -1.66, 17.29; p= 0.10 I2= 28.55%; 41 datapoints/32 articles) and infant consumption of mother’s milk. Certainty of evidence was very low. Narratively, we found mixed results among studies examining maternal BMI and milk production (n=6); three reported an inverse association and three found no association.
Conclusion(s): Mothers with overweight/obesity may be at risk of delayed lactogenesis II, but available data suggest no association with infant consumption. Our results have implications for lactation care and warrant further exploration in mothers with BMI> 30kg/m2.
