Longer Breastfeeding Duration Shown to Reduce Waist Size Over the Long Term

Women who breastfed for longer than 6 months had a smaller waist circumference and body mass index (BMI) compared with women who have not breastfed or have breastfed for a shorter duration, according to the results of a recent study.

In normal pregnancy, a healthy amount of weight gain is recommended; however, too much can contribute to increased insulin resistance and cardiovascular disease risk. Factors contributing to weight gain postpartum include medical comorbidities and physical inactivity. In addition, other factors such as a well-balanced diet, decrease the risk of weight gain.

Breastfeeding is an interesting component in maternal health. Although previous study results show a longer breastfeeding duration to be related to weight loss and healthy body composition, these findings may not be solely caused by breastfeeding, potentially introducing bias in these studies. Propensity scoring analyses is a method used to account for confounding variables on a treatment effect, mitigating much of the bias.

Researchers in this study used this method to determine if women, 7 to 15 years postdelivery, who breastfed for more than 6 months, would have smaller waist circumstances than women who breastfed for 6 months or less.

Of the 676 women analyzed, 38.2% of them did not breastfeed following pregnancy, 22% breastfed between 0 to 3 months, 13.2% breastfed between 3 to 6 months, and 26.6% breastfed for more than 6 months. Mean waist circumferences were not significantly different among patients who breastfed for 6 months or less, so these groups were combined into one.

At the follow-up visit (about 11 years postdelivery), women who breastfed longer than 6 months had lower BMI, blood pressure, and smaller waist and hip circumference compared with women who breastfed for 6 months or less. Women who breastfed longer also had higher diet quality scores and increased hours of physical activity per week and were more likely to not smoke.

Women who did not exhibit central obesity (waist circumference ≥88 cm) breastfed an average 6.4 months, while women who exhibited central obesity breastfed an average 3.9 months. Investigators also found that breastfeeding was associated with a 0.20-cm smaller waist circumference for each additional month of breastfeeding. For women who breastfed for more than 6 months, waist circumference was 4.4 cm smaller than women who did not breastfeed and 3.5 cm smaller than women who breastfed for ≤6 months. BMI was also lower by 1.6 kg/m² in women who breastfed for more than 6 months compared with women who breastfed for a shorter duration.

After accounting for confounding variables, investigators still found a significant correlation between the duration of breastfeeding and waist circumference. Because of the health hazards that central obesity imposes, breastfeeding duration should be investigated further to conclude whether it impacts long-term maternal health.

Reference

Snyder GG, Holzman C, Sun T, Bullen B, Bertolet M, Catov JM. Breastfeeding greater than 6 months is associated with smaller maternal waist circumference up to one decade after delivery [published online November 27, 2018]. J Womens Health (Larchmt). doi: 10.1089/jwh.2018.7393.