Background

Infant feeding and sleep affect childhood BMI, but few studies have assessed the longitudinal relationships between these factors. We aimed to assess the effects of sufficient sleep at 3 months and breastfeeding at 6 months on BMI percentile in early childhood in a prospective national sample.

Methods

We examined data from the National Children’s Study Vanguard Study, a prospective cohort assessing influences on child health and development. Parents reported day and night sleep quantities at 3 months and whether the infant was breastfeeding at 6 months. We categorized sleep as sufficient at 3 months if parents reported greater than or equal to 14 hours combined daytime and nighttime sleep. BMI percentile after 2 years was a continuous outcome. Adjusted logistic regression assessed the relationship between sleep sufficiency at 3 months and breastfeeding at 6 months. Linear regression models assessed the relationship between breastfeeding and BMI percentile, with and without adjustment for sleep sufficiency. All models were adjusted for income, race/ethnicity, child sex, siblings in the household, gestational age at birth, and birthweight.

Results

Among infants with both sleep and feeding data (n=1788), over half (60%) of infants were reported to have sufficient sleep at 3 months of life and 55% were still being breastfed at 6 months. Mean BMI percentile after age 2 (range 24-42 months) of the overall sample was 51% (SD 30%). Infant sleep sufficiency was significantly associated with breastfeeding at 6 months (aOR 1.3, 95% CI: 1.1, 1.6). Among those with complete data (n=268) breastfeeding affected BMI percentile after 2 years, with those infants still breastfed at 6 months having a BMI percentile 12% lower (95% CI: -19, -5) when not adjusting for sleep sufficiency and 14% (95% CI: -23, -6) when adjusting for sleep sufficiency at 3 months.

Conclusions

Sleep sufficiency and breastfeeding have significant effects on BMI percentile in early childhood in a nationally-representative sample.