Does lactation protect mothers against metabolic syndrome? Findings from the Tehran Lipid and Glucose Study

Aim: We aimed to explore the effect of lactation on development of metabolic syndrome in a prospective population-based study. Methods: From among 4028 female participants of the Tehran Lipid and Glucose Study, aged 1550 years, without metabolic syndrome at the initiation of the study, 925 women were randomly selected to fill out the lactation questionnaire. Women were assigned to five groups based on lactation duration including: none, 16 months, 712 months, 1323 months and 24 months or more. Over a 9-year follow-up, metabolic syndromewas compared between these groups, before and after adjustment for possible confounding variables. Results: Metabolic syndrome was developed in 12.1% of non-lactating women; it was 28.6%, 34.0%, 26.2% and 26.7% in women with 16, 712, 1323 and 24 months or more of lifetime duration of lactation, respectively (P < 0.002). Adjustment for confounders revealed that women with 16 and 712 months of duration of lactation had significantly higher odds of metabolic syndrome in comparison to 24 months or more (1.4 and 1.3 times, respectively). Conclusion: It seems that the longer duration of lactation up to 12 months may protect women against metabolic syndrome, in a doseresponse manner.