Breastfeeding for longer periods may boost its cardiovascular and metabolic benefits for new moms, particularly those who had gestational diabetes researchers found.
Women without gestational diabetes who lactated for more than nine months had half the metabolic syndrome incidence rate of those who didn’t breastfeed at all or quit after a month, according to a population-based study published online in Diabetes.
For women who had gestational diabetes during pregnancy — a particularly vulnerable group — more than nine months of breastfeeding was associated with a reduction in the incidence of metabolic syndrome to one-sixth the rate of similar women with one month or less of lactation.
The findings provide the some of the first direct evidence for long-term cardiometabolic benefits, according Erica P. Gunderson, PhD, of Kaiser Permanente in Oakland, Calif., and colleagues.
The results also affirm the improved cholesterol and insulin profiles observed during lactation in other studies and epidemiological evidence for a weak to modest protective effect that can extend to mid- and later life.
The strong protective effect seen in this study may put it on par with other key interventions to reduce metabolic syndrome risk, such as weight loss, diet, and exercise, Gunderson said in an interview. However, she cautioned that breastfeeding should be considered in combination with other lifestyle efforts, rather than as a replacement for them
We know that lactation and breastfeeding of a child has so many important health benefits,” Gunderson noted. “This is one additional benefit for their [the mothers'] own health.”
Gunderson’s group analyzed findings from the longitudinal, population-based CARDIA (Coronary Artery Risk Development in Young Adults) study.
They examined metabolic syndrome incidence over 20 years of follow-up for 1,399 women ages 18 to 30 who had no biological children at baseline and no preexisting metabolic syndrome.
Among the 704 women who had at least one child during the study period, 120 cases of incident metabolic syndrome developed, for an incidence rate 12.0 per 1,000 person-years.
Women who never had any children had a metabolic syndrome incidence rate of 11.1 cases per 1,000 person-years, which was not significantly different from parous women.”
The 84 women who had gestational diabetes were more likely to go on to a diagnosis of metabolic syndrome, with an incidence rate of 22.1 compared with 10.8 per 1,000 person-years among parous women who didn’t have gestational diabetes (P=0.002).
Metabolic syndrome incidence rates dropped across the board with a longer duration of breastfeeding. Lactation for more than one month lowered the incidence of metabolic syndrome by 39% to 56% for women who didn’t develop gestational diabetes and by 44% to 86% for those who did.
But the effect was sufficiently greater for those who had gestational diabetes that breastfeeding for more than nine months erased the excess risk associated with having had gestational diabetes.
For women without gestational diabetes, incidence was 15.8 per 1,000 person-years (95% CI 11.3 to 21.5) if they lactated for no more than one month compared with 9.2 (95% CI 5.3 to 14.6) if they breastfed their children for more than nine months.
For women with gestational diabetes, incidence dropped from 49.4 per person-years (95% CI 25.8 to 84.7) when lactation duration was no more than one month down to 8.5 (95% CI 1.8 to 24.8) for those who breastfed for more than nine months.
The breastfeeding period remained protective after adjustment for race and baseline (preconception) age, education, smoking, body mass index, all components of the metabolic syndrome, and physical activity (all P=0.03).
However, the researchers noted that the study was limited by lack of data on exclusivity or intensity of breastfeeding and by use of self-reporting for gestational diabetes.
Also, women who breastfed had generally healthier lifestyles than those who didn’t, suggesting that residual confounding may have contributed to the findings, they wrote.
The mechanism for the link between lactation and metabolic syndrome needs further study, but there is some evidence for greater postpartum weight loss and preferential loss of abdominal fat with breastfeeding, they concluded.
The study was funded by the National Institutes of Health through contracts with the National Heart, Lung, and Blood Institute and a career development award; a grant from the National Institute of Diabetes, Digestive and Kidney Diseases, and a research award from the American Diabetes Association.
The researchers reported no conflicts of interest.
By Crystal Phend, Senior Writer, MedPageToday
Reviewed by Zalman S. Agus, MD; Emeritus Professor University of Pennsylvania School of Medicine.
December 03, 2009
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