Women with prior gestational diabetes who fed their newborns at least 80% breast milk had more favorable lipid profiles and cardiometabolic markers in the first 3 months following birth, according to a recent study published in JAMA Network Open.

The women had reduced odds of hypertriglyceridemia than women who breastfeed with less intensity in the first 3 months after delivery, indicating a dose-response relationship between breastfeeding and postpartum lipids.

“Women with prior gestational diabetes are increasingly recognized as being at elevated long-term cardiovascular risk. Our findings raise the possibility that breastfeeding may be one component of early postpartum strategies aimed at improving lifelong cardiometabolic health,” said Ichiro Yasuhi, MD, OB/GYN at National Hospital Organization Nagasaki Medical Center in Omura, Japan, who worked on the study.

Gestational diabetes affects approximately 14% of pregnancies globally and is associated with an increased risk for type 2 diabetes, dyslipidemia, and cardiovascular disease.

Routine glucose testing is recommended for those with previous gestational diabetes as part of postpartum and long-term primary care, and the American Diabetes Association and the Endocrine Society encourage breastfeeding. Previous studies established a positive association between breastfeeding duration and improved outcomes for cardiovascular health and lower incident rates of nonalcoholic fatty liver disease. However, Yasuhi said more research was needed to understand whether breastfeeding intensity was associated with maternal lipid metabolism.

The cohort study included 470 Japanese women (average age, 34 years; average prepregnancy BMI, 23.7) who had gestational diabetes during pregnancy.

Data were collected during a follow-up visit between 6 and 9 weeks postpartum from 2014 to 2020 at a tertiary medical center. The patients reported on the diet of their newborn, which was categorized into six levels on a scale measuring breastfeeding intensity.

Yasuhi and his team defined “high-intensity breastfeeding” as breastfeeding in which 80% or more of their baby’s diet was breast milk (79%). The remaining 21% either breastfed less or not at all.

Patients also underwent a 75-g oral glucose tolerance test and fasting lipid assessment.

High-intensity breastfeeding was associated with reduced odds of hypertriglyceridemia (adjusted odds ratio, 0.25; 95% CI, 0.13-0.51; P < .001) and had lower triglyceride levels (67.2 vs 116.1 mg/dL; P < .001) and better low-density lipoprotein cholesterol (LDL-C) to high-density lipoprotein cholesterol (HDL-C) ratios (1.8 vs 2.3, P < .001) than women who fed infants less than 80% breast milk. The associations persisted after adjusting for patients’ insulin sensitivity.

Results also showed an intensity-dependent association. As breastfeeding intensity decreased across the six levels, all measures progressively worsened.

Women who provided their babies with 60%-70% breast milk had lower triglyceride levels than those who fed their babies less than 50% breast milk (108 vs 128 mg/dL; P < .001), and lower LDL-C to HDL-C ratios (2.2 vs 2.4; P < .001).

While the results are promising for women who can breastfeed successfully, women who have gestational diabetes are at high risk for having difficulties breastfeeding, said Candy Lincoln, MD, family medicine physician who specializes in breastfeeding medicine at MU Health Care in Columbia, Missouri.

“This population is a high-risk group for having difficulties with lactation, either slow to start out with breastfeeding or having trouble achieving a full milk supply,” Lincoln said.

Results from the study also may not apply to the US, where obesity rates are high because participants had low BMIs going into pregnancy.

“If we present patients with this kind of information, it could easily turn into a situation where the patient feels shamed, especially if she can’t reach the breastfeeding goal,” Lincoln said.

Clinicians should counsel patients that even those who breastfed less than 80% showed better outcomes than those who did not breastfeeding at all.

“Ultimately, whether and how much to breastfeed should remain the mother’s decision, supported — rather than prescribed — by her healthcare team,” Yasuhi said.

Yasuhi and Lincoln reported having no financial conflicts of interest.

Kelsey Mesmer, PhD, is a freelance journalist and journalism professor at Saint Louis University in St. Louis.