CARDIA Study: Lactation Duration Inversely Associated with Diabetes Progression in Women across the Childbearing YearsPublished on: 16 Feb 2018BookmarkPDFSHAREListenBackgroundStudies have demonstrated a weak association between lactation duration and reduction in the risk of incident diabetes (3%-15% lower incidence per year of lactation) in middle-aged to older women. With the lack of biochemical evidence to support this association, the risk estimates appear to be biased due to various confounding factors including gestational diabetes (GD), perinatal outcomes, and differences in lactation duration across the childbearing years.AimThe CARDIA (Coronary Artery Risk Development in Young Adults) study assessed the association between lactation and progression to diabetes using biochemical testing both before and after pregnancyStudy Participant ProfileYoung black (n=615) and white (n=623) women (age; 18 to 30 years) without diabetes at baseline with 1 or more live births after baseline and reporting lactation duration (n=1238)Participants were categorized as per the time-dependent lactation duration as follows:None (n=322, 26%)More than 0 to 6 months (n=418, 33.8%)More than 6 months-to less than 12 months (n=268, 21.6%)12 months or more (n=230, 18.6%)Screening/Follow-upStudy participants were screened for diabetes up to 7 times during 30 years after baselineMethodStudy DesignMulticenter, community-based 30-year prospective cohort studyOutcomesDiabetes incidence rates per 1000 person-yearsRelative hazards (RH) of diabetes, adjusted for biochemical, sociodemographic, and reproductive risk factors and other factors such as family history of diabetes, lifestyle, and weight change during follow-up.ResultsOne hundred and eight two incident diabetes cases were reported during 27598 person-years. This corresponded to an overall incidence rate of 6.6 cases per 1000 person-years.Incidence rate (/1000 person-years) of diabetes was higher in women with GD vs. those without GD (18.0 vs. 5.1, P for difference < 0.001).Lactation duration had a strong, graded inverse association with diabetes incidence (P for trend = 0.01) (Table 1)Table 1: Adjusted RH of diabetes for lactation duration categories vs. no lactationLactation Duration Adjusted RHRisk Reduction0 to 6 months0.7525%More than 6 months to less than 12 months0.5248%12 months or more0.5347%No lactation was associated with a per year excess risk of incident diabetes of 2.08% in women with GD history and 0.48% in women without GD history as compared to lactation for a duration of 12 or more months.ConclusionsLactation duration was independently associated with lower incidence of diabetes.Strategies to increase and improve breastfeeding practices are warranted to mitigate the risk of chronic diseases such as diabetes in women.