The researchers attribute the link to the involvement of the hormones prolactin and oxytocin that play important roles during lactation along with the benefits of weight loss to women who breastfeed.
“Breast milk is packed with different hormones, antibodies, stem cells, enzymes, and nutrients that may be driving these benefits, which is worthy of further scientific study,” says Dr Adam Lewandowski, Associate Professor of Cardiovascular Science at the University of Oxford, who was not involved in the study.
“The evidence suggests that women should be offered more breastfeeding support to enhance their health and that of their child.”
‘An excellent group’
Prof Naveed Sattar, Professor of Metabolic Medicine at the University of Glasgow adds: “This work comes from an excellent group.
“The top line results are not surprising given women who chose to breast feed will have several other lifestyle habits that reduce heart disease risks compared to women who chose not to, and many of these factors are not easily accounted for in the research methods.
“Breast feeding can help women lose weight and long-term weight trajectories are highly relevant to heart disease, cancers and type 2 diabetes, all of which occur less in women who chose to breast feed.
“So there may be both direct and indirect reasons for why women who chose to breast feed are at lower risk of heart disease or stroke.”
The researchers from the Medical University of Innsbruck, Austria reviewed data from eight studies conducted between 1986 and 2009 in Australia, China, Norway, Japan and the U.S. and one multinational study.
The review included health records for nearly 1.2 million women (average age 25 at first birth) and looked at the relationship between breastfeeding and the mother's individual cardiovascular risk.
These records include information on how long women had breastfed during their lifetime, the number of births, age at first birth and whether women had a heart attack or a stroke later in life or not.
11% decreased risk
The main findings revealed that out of the 82% of the women who breastfed at some time in their life had a 11% decreased risk of developing cardiovascular disease versus women who never breastfed.
Over an average follow-up period of 10 years, women who breastfed were 14% less likely to develop coronary heart disease; 12% less likely to suffer strokes; and 17% less likely to die from cardiovascular disease.
Additional findings include women who breastfed for 12 months or longer during their lifetime appeared to be less likely to develop cardiovascular disease than women who did not breastfeed.
There were no notable differences in cardiovascular disease risk among women of different ages or according to the number of pregnancies.
“It's important for women to be aware of the benefits of breastfeeding for their babies' health and also their own personal health," explains senior author Dr Peter Willeit, Professor of Clinical Epidemiology at the University.
"Moreover, these findings from high-quality studies conducted around the world highlight the need to encourage and support breastfeeding, such as breastfeeding-friendly work environments, and breastfeeding education and programs for families before and after giving birth."
"It should be particularly empowering for a mother to know that by breastfeeding she is providing the optimal nutrition for her baby while simultaneously lowering her personal risk of heart disease," adds Shelley Miyamoto, Chair of the American Heart Association's Council on Lifelong Congenital Heart Disease and Heart Health in the Young (Young Hearts).
First author Lena Tschiderer, a postdoctoral researcher at the University concludes: “A limitation of this meta-analysis is that little information was available about women who breastfed for longer than two years.
"If we had this additional data, we would have been able to calculate better estimates for the association between lifetime durations of breastfeeding and development of cardiovascular disease in mothers."
Source: Journal of the American Heart Association
Published online: DOI: 10.1161/JAHA.121.022746
“Breastfeeding is associated with a reduced maternal cardiovascular risk: Systematic review and meta-analysis involving data from eight studies and 1,192,700 parous women’
Authors: Lena Tschiderer et al