Sustained Reduction of Subclinical Inflammation in the Years After Breastfeeding.

CONTEXT

Lactation is associated with lower future risk of cardiovascular disease (CVD) in women but the mechanism(s) underlying this relationship remain unclear.

OBJECTIVE

We sought to characterize the relationship between duration of exclusive breastfeeding and CV risk factors over the first 5 years post partum.

METHODS

In this prospective cohort study, 328 women underwent serial cardiometabolic characterization (anthropometry, blood pressure [BP], lipids, fasting glucose, adiponectin, C-reactive protein [CRP]) at 1 year, 3 years, and 5 years post partum. Outcomes were CV risk factors in 3 groups defined by duration of exclusive breastfeeding: less than 3 months (n = 107), 3 to 6 months (n = 101), and 6 months or more (n = 120).

RESULTS

The prevalence of metabolic syndrome did not differ between the groups at 3 years but, by 5 years post partum, was higher in women who had exclusively breastfed for less than 3 months than in those who did so for 3 to 6 and 6 months or more, respectively (14.0% vs 6.9% vs 4.2%; P = .02). However, after adjustment for covariates (including body mass index [BMI]), there were no statistically significant differences between groups in BP, glucose, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, or adiponectin. Indeed, the only CV risk factor difference that persisted after covariate adjustment was that women who had exclusively breastfed for less than 3 months had higher CRP both at 3 years (P = .04) and 5 years (P = .01). Moreover, generalized estimating equation analyses with adjustment for covariates (including time-dependent BMI) showed that CRP remained higher over time in these women, as compared to their peers, from 1 year to 3 years to 5 years post partum (P = .03).

CONCLUSION

Sustained reduction of subclinical inflammation may contribute to the cardioprotective effect of lactation in women.