Consistent lactation lowers maternal vascular risk

Breastfeeding may protect mothers against the development of vascular disease, according to a recent study. The new data add to existing data for the long-term health benefits of lactation.

The new finding comes from 297 women, 45 to 58 years old, who were enrolled in an ancillary study to the Study of Women Across the Nation (SWAN), called SWAN-Heart. SWAN is a community-based cohort study of racially diverse women conducted at 7 sites across the United States; SWAN-Heart participants were enrolled only at the Pittsburgh and Chicago sites. Women in SWAN reported at least 1 live birth at enrollment and were free of cardiovascular disease at entry.

Lactation history was assessed at enrollment and was self-reported. It was classified as no lactation, inconsistent lactation (breastfeeding at least 1 child for less than 3 months), and consistent lactation (breastfeeding each child for 3 months or more).

Ultrafast CT provides a measure of calcification; in SWAN-Heart, calcification of the aorta and coronary arteries was assessed. B-mode ultrasonography was used to assess carotid adventitial diameter, carotid intima-media thickness, and carotid plaque.

After adjusting for age, parity, measures of socioeconomic status, and lifestyle and family history, a significant association was observed between aortic and coronary calcification and consistent lactation for 3 months postpartum, reported Eleanor Bimla Schwarz, MD, MS, assistant professor, medicine, and obstetrics, gynecology, and reproductive sciences, University of Pittsburgh, and colleagues.

The odds of aortic calcification was increased by a factor of 3.85, and the odds of coronary artery calcification by 2.78 in the mothers who did not breastfeed compared to the mothers who consistently breastfed. The association between lactation and less aortic calcification persisted after adjusting for body mass index and traditional cardiovascular risk factors. In fact, after adjusting for all potential confounders, the risk of aortic calcification increased by more than 5-fold in the mothers who did not breastfeed compared to those who consistently breastfed.

The authors wrote: "These findings build on previous work that has shown that women who do not breastfeed are at greater risk of clinical cardiovascular disease, by providing insight in to the early effects of lactation on a mother's body."

They speculate that the effects of lactation on prolactin and oxytocin may have positive long-term effects on cardiovascular risk profiles because these hormones have been shown to be associated with blood pressure, preclinical atherosclerosis, and vascular resistance.

Schwarz EB, McClure CK, Tepper PG, et al. Lactation and maternal measures of subclinical cardiovascular disease. Obstet Gynecol. 2010;115(1):41-48.