Breastfeeding Intensity and Early Postpartum Lipid Profiles Among Women With Prior Gestational Diabetes

Importance: Women with prior gestational diabetes are at high risk of cardiometabolic disease, including dyslipidemia, early in the postpartum period. Identifying modifiable factors associated with lipid metabolism is clinically important. Objectives: To examine the association between breastfeeding intensity and early postpartum lipid profiles and assess whether these associations persist after adjustment for insulin sensitivity. Design, Setting, and Participants: This prospective cohort study included Japanese women with prior gestational diabetes who underwent metabolic evaluation at 6 to 9 weeks post partum at a tertiary medical center from December 1, 2014, to November 30, 2020. Statistical analysis was conducted from April 2024 to June 2026. Exposures: Breastfeeding intensity categorized using a validated 6-level scale. High-intensity breastfeeding (HIB) was defined as 80% or more breast milk. Main Outcomes and Measures: Fasting lipid profiles and dyslipidemia defined according to Japan Atherosclerosis Society criteria. Associations were evaluated using multivariable regression models adjusting for clinical covariates and insulin sensitivity (Matsuda index). Results: Of 470 women in the study (mean [SD] age, 34.0 [4.8] years), 369 (79%) practiced HIB. HIB was associated with lower mean (SD) triglyceride levels (67.2 [42.0] vs 116.1 [66.7] mg/dL; P < .001), higher mean (SD) high-density lipoprotein cholesterol (HDL-C) levels (73.9 [17.8] vs 63.0 [14.0] mg/dL; P < .001), and lower mean (SD) high-density lipoprotein cholesterol (LDL-C) to HDL-C ratios (1.8 [0.7] vs 2.3 [0.7]; P < .001) compared with those not practicing HIB. In adjusted analyses, HIB was associated with reduced odds of hypertriglyceridemia (adjusted odds ratio [AOR], 0.25; 95% CI, 0.13-0.51) and elevated LDL-C to HDL-C ratio (AOR, 0.27; 95% CI, 0.15-0.49). These associations remained significant after adjustment for insulin sensitivity. Conclusions and Relevance: This study found that HIB was associated with more favorable early postpartum lipid profiles after adjustment for insulin sensitivity among women with prior gestational diabetes, suggesting that greater breastfeeding intensity is associated with a more favorable early cardiometabolic profile among women with prior gestational diabetes.