Early breastfeeding linked to lower risk of childhood obesity, regardless of mother's weight, study finds

Consistently breastfeeding infants in any amount during their first three months was associated with a lower risk of childhood obesity, regardless of the mother's body mass index (BMI) before pregnancy, according to a new study.

The research is published in the journal Pediatrics.

While previous studies have shown that breastfeeding may protect children against obesity and other chronic conditions, this relationship has not been studied much in women with obesity. ECHO Cohort researchers wanted to explore the possible link between breastfeeding practices in women with obesity and overweight before pregnancy and a child's BMIz score. Researchers use BMIz scores to compare children's height and weight to those of their peers, while the more familiar BMI assesses body weight in relation to height.

In this ECHO Cohort study, researchers found that any amount of consistent breastfeeding during an infant's first three months was associated with lower BMIz scores, calculated later at ages between 2 and 6 years, regardless of the mother's pre-pregnancy BMI. This protective association appeared stronger for children with mothers who had obesity before pregnancy compared to those categorized as overweight during the same time. (A BMI of 25 to 29.9 is considered overweight, and a BMI of 30 or higher is considered obese.)

"Our findings highlight that each additional month of breastfeeding, whether a consistent amount or exclusively, may contribute to a lower weight later in childhood, especially for mothers who had obesity before pregnancy," said Gayle Shipp, Ph.D., RDN of Michigan State University.

The study looked at BMI measurements from 8,134 pairs of mothers and kids at 21 study sites in 16 states and Puerto Rico. The researchers calculated BMI and BMIz scores from measurements taken at study visits, medical records, or self-reported data for the mother and child. Additionally, the study examined two breastfeeding situations: whether the mother ever breastfed or whether the mother was exclusively breastfeeding the infant at 3 months old. This continuous breastfeeding measure included the duration of any breastfeeding allowing for formula or other food and the duration of exclusive breastfeeding with no formula feeding or other food.

Exclusive breastfeeding at three months was associated with a lower child BMIz score only among women with a pre-pregnancy BMI in the normal range. Each additional month of any or exclusive breastfeeding correlated with a significantly lower child BMIz, particularly for mothers categorized as overweight (in the case of any breastfeeding) or as having obesity (for any or exclusive breastfeeding) prior to pregnancy.

"Health professionals can use this study's findings as an opportunity to encourage and promote breastfeeding among all women, especially those who have obesity," said Shipp.