Postmenopausal women who breastfed for at least 6 months cumulatively have a significantly lower incidence of subclinical atherosclerosis compared to postmenopausal women who breastfeed for a shorter duration, according to a cross-sectional study in the journal Gynecological Endocrinology.
This finding was independent of traditional cardiovascular risk factors.
The investigators assessed the connection between a history of breastfeeding and indices of subclinical atherosclerosis in 197 parous postmenopausal women (mean age 55.7 years) with a history of breastfeeding.1
All study patients were treated at the Menopause Clinic of the Aretaieio Hospital, University of Athens, Greece.
Subclinical atherosclerosis was diagnosed via pulse wave velocity (PWV), intima-media thickness [IMT] and the presence of atherosclerotic plaque.
Compared to women who reported breastfeeding for only 1 to 5 months, women who reported doing so for at least 6 months had significantly lower values for common carotid artery IMT: model R2 = 15.7%, b-coefficient = -0.170; 95% confidence interval (CI): -0.208 to -0.001 (P = 0.019).
Furthermore, after adjusting for traditional risk factors, women with a longer duration of breastfeeding were much less likely to have subclinical atherosclerosis: model X2 = 28.127, odds ratio (OR) = 0.491; 95% CI: 0.318 to 0.999 (P = 0.049).
However, the prevalence of plaques in carotid arteries was not linked to breastfeeding: 16.2% among women with longer breastfeeding duration vs. 19.7% for shorter duration (P = 0.528 chi squared).
“The pathophysiological pathways mediating our findings are difficult to be established,” wrote the authors. “Breastfeeding women have higher circulating prolactin, a hormone shown to stimulate maternal beta-cell proliferation in pregnant mice.”
A recent analysis of data from the Nurses’ Health Study found that women with baseline prolactin levels in the highest quartile were less likely to develop diabetes later in life compared to women whose prolactin levels were in the other quartiles.
In addition, oxytocin, “released by the posterior pituitary upon nipple stimulation by the lactating infant, has been shown to lower the reactivity of the autonomous nervous system to stress and therefore regulates blood pressure,” wrote the authors.
Other studies support the benefits of breastfeeding in decreasing the risk for overt cardiovascular disease, including the European Prospective Investigation into Cancer and Nutrition (EPIC), which found that a personal history of breastfeeding was associated with a 29% lower risk of coronary events compared to the risk in women who had never breastfed.
The second Nord-Trøndelag Health Survey (HUNT2) also concluded that women who never breastfed were 2.5 times more likely to experience a fatal cardiovascular event as opposed to women who breastfed for at least 24 months, after adjustment for the number of pregnancies, cardiovascular risk factors and social factors.
Likewise, the Study of Women’s Health Across the Nation (SWAN) found a 5.26-fold higher risk for aortic calcification in women with no personal history of lactation versus women who had breastfed.
The current investigators noted that a longer duration of breastfeeding may have a beneficial effect on subclinical atherosclerosis later in life.
“If this association indicated by the study is causative, the history of breastfeeding could aid as prognostic marker for prediction of future cardiovascular risk,” the authors concluded.