(P31-008-23) Associations of Maternal Body Mass Index With Human Milk Metabolome in Exclusively Breastfeeding Rural Bangladeshi Women

Objectives: Evaluate the associations of postpartum maternal body mass index (BMI) with breast milk (BM) metabolome at 1 & 4 months postpartum in rural Bangladeshi women.

Methods: In a pregnancy birth cohort in rural Sylhet district, Bangladesh, we collected mid-feed BM from lactating women (94 at 1 month and 88 at 4 months postpartum). At both visits, we categorized women into underweight (UW, BMI < 18.5 kg/m²), normal (BMI 18.5–22.9 kg/m²), or overweight/obese (OWOB BMI >22.9 kg/m²) per Asia Pacific standards. We performed untargeted BM metabolomics and identified 568 and 566 metabolites at 1 month and 4 months postpartum. We used principal component analysis to consolidate metabolites into 6 “factors” accounting for 41% and 39% of the total variance at 1 and 4 months. We used generalized linear regression to quantify associations of BMI category with factor scores. Through enrichment analysis (Metaboanalyst 5.0) we identified biological pathways among the top 15 most differential metabolites. Statistical significance was set using Bonferroni-corrected p-value for multiple comparisons.

Results: At 1 and 4 months postpartum respectively, 24.4% and 17.0% of participants were OWOB, and 13.8% and 18.1% were UW. At 1 month, maternal OWOB (vs. normal) BMI status was associated with 0.83 (p= 0.0006) unit decrease in factor 5, which was comprised mainly of amino acids (AA). Metabolic pathways significantly enriched in factor 5 included AA metabolism, glutathione metabolism, and homocysteine metabolism. At 4 months, OWOB (vs. normal) BMI status was associated with 0.66 (p= 0.018) unit increase in factor 4, which was comprised mainly of AA. Metabolic pathways significantly enriched in factor 4 included AA metabolism and betaine metabolism pathways significantly enriched in factor 4. BM metabolomics did not differ between normal vs. UW BMI groups.

Conclusions: Maternal OWOB is associated with differences in the BM metabolome, particularly AA, and antioxidant-related pathways. Future studies should examine associations of milk composition with infant outcomes.

Funding Sources: This research was supported by grants from the Massachusetts Life Sciences Center, Brigham and Women’s Hospital, and the National Institute of Child Health and Human Development (NICHD).