Background: Little is known about how maternal obesity impacts breast milk (BM) composition and how BM composition may impact growth. We sought to determine the role of maternal body mass index (BMI) on BM inflammatory and oxidative stress markers and to delineate the role of these BM markers on infant growth.
Methods: This was a secondary analysis of 40 mother-infant dyads. We first assessed the association between maternal BMI and BM marker (omega-6:omega-3 polyunsaturated fatty acid ratio (n-6:n-3 PUFA), leptin, interleukin (IL)-8, IL-6, IL-1β and malondialdehyde (MDA)) concentration at one (V1) and four (V4) months postpartum. We then examined the association between BM markers on infant growth trajectory from birth to seven months.
Results: Higher maternal BMI was associated with higher BM n-6:n-3 PUFA (V1 β = 0.12, 95% CI 0.01, 0.2; V4 β = 0.13, 95% CI 0.01, 0.3) and leptin (V1 β = 107, 95% CI 29, 184; V4 β = 254, 95% CI 105, 403) concentrations. Infants exposed to high BM n-6:n-3 PUFA had higher BMI z-scores over time (p = 0.01). Higher BM leptin was associated with lower infant percent fat mass at V4 (β = -9, 95% CI -17, -0.6). Infants exposed to high BM IL-8, IL-6, or IL-1β had higher weight z-scores over time (IL-8 p < 0.001; IL-6 p < 0.001; IL-1β p = 0.02). There was no association between BM MDA and maternal BMI or infant growth.
Conclusions: Higher maternal BMI is associated with higher BM n-6:n-3 PUFA and leptin concentrations. In addition, higher BM n-6:n-3 PUFA and inflammatory cytokines were associated with accelerated weight gain in infancy.