Breastfeeding and the mother's heart: after 10-14 years, breastfeeding mothers have a lower estimated risk of heart attack and stroke

In an analysis of data from the long-term HAPO Follow-Up project published in Obstetrics & Gynecology, researchers looked at whether past breastfeeding was associated with the estimated long-term risk of atherosclerotic cardiovascular disease (ASCVD) in the same women 10 to 14 years after giving birth, and whether this association differed in those who had gestational diabetes mellitus (GDM) during pregnancy. Of the 4,540 participants (median age at enrollment was 30.6 years), about 80% reported having breastfed. After an average of 11.6 years, women who had breastfed had a lower estimated 10-year risk of ASCVD (2.3% vs. 2.5%; adjusted difference β = -0.13 pp) and 30-year risk (6.2% vs. 6.9%; β = -0.36 pp). Moreover, the effect was noticeably stronger in those who had suffered from GDM.

Background of the study

Cardiovascular disease remains the leading cause of death in women, and pregnancy has long been considered a “stress test” for the cardiovascular system. Major reviews and position papers from the American Heart Association emphasize that adverse pregnancy outcomes—gestational diabetes mellitus (GDM), hypertensive disorders, and preterm birth—are associated with increased long-term risk of coronary heart disease, stroke, and heart failure in the mother. Therefore, guidelines suggest considering such pregnancy histories as risk modifiers for subsequent CVD prevention.

Against this background, breastfeeding has long ceased to be a topic of only children's health. Lactation requires additional energy (about 340-500 kcal/day), is accompanied by improved insulin sensitivity and favorable shifts in the lipid profile - physiological mechanisms that can leave a "cardiometabolic trace" in the mother years after childbirth. Professional and public sources (CDC, NIH) agree in assessing the increased energy requirement and potential metabolic benefits of lactation.

This biology echoes epidemiology: a JAHA systematic review and meta-analysis (8 prospective studies, 1.19 million women) found that “ever breastfeeders” had a lower risk of major CV events compared with “never breastfeeders” (pooled odds ratios: 0.89 for all CVD, 0.86 for CHD, 0.88 for stroke, 0.83 for fatal CVD) and that longer cumulative duration of breastfeeding was associated with greater protection. These findings are supported by AHA press materials and other reports.

A separate important group is women with GDM: their baseline risk of subsequent type 2 diabetes and CVD is above average, and meta-analyses record an increase in the postpartum risk of CVD already in the first years after pregnancy and over the course of decades. Against this background, the question “does lactation provide an additional reduction in maternal cardiac risk, especially after GDM?” is clinically significant: if the answer is positive, breastfeeding support becomes part of the planned prevention of CVD in high-risk women, along with monitoring body weight, blood pressure, lipids, and glycemia.

This is why studies that look not only at “hard” events after 20-30 years, but also at standardized cardiac risk scales in the medium term (10-30 years) in the same women are relevant - to understand whether lactation leaves a discernible trace in the integrated risk assessment and whether this effect is modified by previous GDM.

How risk was calculated and why it is important

The authors did not wait for real heart attacks and strokes - they calculated the Framingham Risk Score 10-14 years after childbirth (i.e. at a relatively young age), obtaining an estimate of the probability of a fatal/non-fatal coronary event or stroke on 10- and 30-year horizons. This approach provides an early "thermometer" of cardiac risk and allows us to see whether lactation leaves a metabolic "trace" in the mother herself for a long time. The result: any lactation (yes/no) was associated with a lower estimated risk both 10 and 30 years ahead after adjustments for age, BMI, smoking/alcohol, parity, and other pregnancy variables.

Who benefited more?

The most interesting thing is the modification of the effect by gestational diabetes. In women with GDM, breastfeeding was “accompanied” by a greater decrease in the estimated 10-year risk (β = -0.52 pp) and 30-year risk (β = -1.33 pp) than in women without GDM (-0.09 and -0.25 pp, respectively; the differences are statistically significant, P for interaction 0.004 and 0.003). This is biologically logical: lactation helps to expend energy, improves insulin sensitivity, accelerates the reverse changes in lipid and carbohydrate metabolism after pregnancy - namely, those who have had GDM have the longest metabolic “tails”.

What's new compared to previous works

Previously, a large meta-analysis article in the Journal of the American Heart Association (1,192,700 women) had already shown that those who had breastfed were less likely to suffer from CVD in subsequent years. The latest publication clarifies the picture: the effect is visible in the same woman 10-14 years after her birth, already at the level of standardized cardiac risk, and it is stronger in the high-risk group - after GDM. This helps to plan targeted prevention, and not "on average for the hospital."

How to explain this in simple words

Breastfeeding is not just about the baby. For the mother, it is:

• "Metabolic tuning": additional energy and glucose consumption for lactation, improvement of insulin sensitivity and lipid profile.
• Hormonal changes: prolactin/oxytocin and restructuring of the stress response, which indirectly affects the vascular wall and pressure.
• Long-lasting effects: For some women, the changes persist as a more favourable cardiometabolic profile years later, as reflected by the Framingham score. These mechanisms are consistent with previous reviews of the benefits of lactation in reducing the risk of type 2 diabetes and some CVD risk factors.

Research Design - What's Important to Know

This is a secondary analysis of the prospective HAPO Follow-Up.

• Exposure: history of any breastfeeding (yes/no).
• Outcome: Estimated 10- and 30-year Framingham ASCVD risk at ≈11.6 years postpartum.
• Models: multiple linear regression adjusted for center, age, BMI, height, smoking/alcohol, parity, and time from birth to ASCVD assessment; separate testing for interaction with GDM.
• Key figures: 79.7% of participants breastfed; estimated risk reduction by 0.13 pp (10 years) and 0.36 pp (30 years) in the overall group, and more after GDM.

What does this change for practice?

• It is useful for women after gestational diabetes to know that lactation is not only “about today”, but also about cardioprotection for years to come.
• It makes sense for obstetricians and endocrinologists to more actively support breastfeeding in the postpartum period in patients with GDM (joint consultations, assistance from breastfeeding consultants).
• Public health services should consider material and organizational support for breastfeeding as part of the prevention of CVD in women, and not just a pediatric agenda. These findings are consistent with the positions of cardiological communities in recent years.

Restrictions

This is an observational association and estimated risk, not registered heart attacks/strokes. The study did not analyze the duration and “dose” of lactation (exclusivity, months), could not completely remove the influence of lifestyle and social factors, and relied on one scale (Framingham) at a relatively young age. Nevertheless, the consistency with meta-analyses on real events makes the signal convincing at least at the level of a risk biomarker.

What should science test next?

• Dose dependence: how is duration/exclusivity of breastfeeding related to cardiac risk in the mother, especially after GDM.
• Real outcomes: follow cohorts to “hard” events (heart attack, stroke), not just scale scores.
• Mechanisms: Longitudinal metabolomic/lipidomic studies to understand which circuits (insulin, lipids, pressure, inflammation) mediate the effect.
• Equity of access: interventions that improve the coverage and quality of breastfeeding support, particularly in vulnerable groups.

Source: Field C. et al. Association Between Breastfeeding and Long-Term Risk of Cardiovascular Disease. Obstetrics & Gynecology, 2025 May 22; 146(1):11-18. DOI: 10.1097/AOG.00000000000005943