Early Breastfeeding May Reduce Risk of Childhood Obesity, Regardless of Mother's BMI: NIH Study

Human milk exposure via breastfeeding in any amount during the first 3 months of life 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 funded by the Environmental influences on Child Health Outcomes (ECHO) Program at the National Institutes of Health.¹

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Assessed by comparing offspring’s BMIz scores calculated between ages 2 and 6 years, the researchers found the protective association appeared stronger for children whose mothers were categorized as having obesity prior to pregnancy vs those categorized as having overweight.¹

“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,” lead author Gayle Shipp, PhD, RDN of Michigan State University said in an ECHO press release.²

Previous research has shown that breastfeeding may be protective against obesity in childhood but there is very little data on the relationship in women with obesity, according to study authors. Moreover, few studies have had sufficient sample size with which to explore the relationship. ECHO Cohort researchers wanted to explore the possible link between breastfeeding practices in women with obesity and overweight before pregnancy and child BMI for age z-scores (used to compare children’s height and weight to those of their peers) according to maternal pre-pregnancy BMI.¹

Shipp and colleagues looked at BMI measurements from 8134 dyads at 21 study sites in 16 states and Puerto Rico. Study inclusion required data for maternal pre-pregnancy BMI, infant feeding practices, and at least 1 child BMI assessment between ages 2 and 6 years.¹ The researchers calculated BMI and BMIz scores from measurements taken at study visits, medical records, or self-reported data for the mother and child. They also examined 2 breastfeeding situations: whether the mother ever breastfed or whether the mother was exclusively breastfeeding the infant at 3 months of age. 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.¹

FINDINGS¹

The prevalence of pre-pregnancy BMI categories among participants was: healthy weight, 45.8%; overweight, 26.0%; obese, 25.6%; and underweight, 2.5%. Median child ages at the cessation of any breastfeeding across the 4 BMI categories was 19, 26, 24, and 17 weeks, respectively, and at cessation of exclusive breastfeeding across all 4 categories, 12, 20, 17, and 12 weeks, respectively.

The investigators reported that 3 months of any breastfeeding was associated with a lower BMIz score for children whose mothers were a healthy weight (−0.02 [−0.04 to 0.001], P = .06), overweight (−0.04 [−0.07 to −0.004], P = .03), or obese (−0.04 [−0.07 to −0.006], P = .02). They found that 3 months of exclusive breastfeeding was associated with a lower BMIz among children whose mothers were a healthy weight (−0.06 [−0.10 to −0.02], P = .002), overweight (−0.05 [−0.10 to 0.005], P = .07), or obese (−0.08 [−0.12 to −0.03], P = .001).

Shipp et al also found that 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.¹

“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.²

References

1. Shipp GM, Wosu AC, Knapp EA, et al. Maternal pre-pregnancy BMI, breastfeeding, and child BMI. Pediatrics. 2024;153(1):e2023061466. doi:10.1542/peds.2023-061466
2. Early breastfeeding linked to lower risk of childhood obesity, regardless of mother’s weight, NIH study finds. News release. ECHO. January 11, 2024. Accessed January 16, 2024. https://echochildren.org/early-breastfeeding-linked-to-lower-risk-of-childhood-obesity-regardless-of-mothers-weight-nih-study-finds/