Is Maternal Body Weight or Composition Associated with Onset of Lactogenesis II, Human Milk Production, or Infant Consumption of Mother’s Own Milk? A Systematic Review and Meta-Analysis
Bibliographic record
Abstract
Maternal adiposity impacts lactation performance, but the pathways are unclear. We conducted a systematic review to understand whether maternal adiposity (body mass index [BMI] or % fat mass) is associated with onset of lactogenesis II (copious milk; hours), human milk production (expressed volume/24hrs), and infant consumption of mother’s own milk (volume/24hrs). We used random-effects standard meta-analyses to compare the relative risk (RR) of delayed lactogenesis II (>72 hours) between mothers classified as underweight (BMI <18.5kg/m2), healthy weight (BMI 18.5-24.9 kg/m2), and overweight/obese (BMI >25kg/m2) and random-effects meta-regressions to examine associations with hours to lactogenesis II and infant milk consumption. The certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation approach. We included 122 articles. Mothers with underweight (RR: 0.61; 95% CI: 0.46, 0.83; I2= 46.27%; 8 articles/datapoints) or healthy weight status (RR: 0.72; 95% CI: 0.61, 0.84; I2= 64.41%; 15 articles/datapoints) were less likely to experience delayed lactogenesis II than mothers with overweight/obesity. We found no association between maternal BMI and time onset of lactogenesis II (ß= 1.45 hours; 95% CI: -3.19, 6.09; p= 0.52, I2= 0.00%; 8 articles, 15 datapoints). Due to limited data, we narratively reviewed articles examining BMI or % fat mass and milk production (n=6); half reported an inverse association, and half no association. We found no association between maternal BMI (ß= 5.84mL; 95% CI: -11.92, 23.60; p= 0.51, I2= 44.18 %; 58 articles, 75 datapoints) nor % fat mass (ß= 6.54mL; 95% CI: -3.60, 16.68; p= 0.20, I2= 21.40%; 30 articles, 32 datapoints) and infant milk consumption. Certainty of evidence for all outcomes was very low. In conclusion, mothers with overweight/obesity may be at risk of delayed lactogenesis II. Available data do not support an association with infant milk consumption but included studies do not adequately represent mothers with obesity. 285344 While results suggest mothers with overweight/obesity may be at risk of delayed lactogenesis II, it is important to note that available data do not adequately represent mothers at the higher end of the BMI and % fat mass spectrum (BMI >30 kg/m2, % fat mass >40%). Future research should explore the association between maternal body weight or composition and lactation outcomes including onset of lactogenesis II, human milk production and infant consumption of mother’s own milk among mothers with greater variability in weight status. Understanding these relationships may help guide the creation of more specialized lactation care for mothers of all body sizes.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.012 | 0.037 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.018 | 0.037 |
| Bibliometrics | 0.004 | 0.006 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".