Decelerated early growth in infants of overweight and obese mothers

Abstract

Background: Maternal obesity and overweight now affect a majority of US pregnancies. Evidence indicates that excess maternal weight increases offspring risk of obesity. Patterns of infant weight gain and growth also impact obesity risk; however, the effects of maternal pre-pregnancy BMI on early infant growth and body composition have not previously been well characterized. Objective: To determine the relationship between maternal pre-pregnancy BMI category and infant growth and body composition. Methods: Non-diabetic mothers with singleton pregnancies were recruited in pregnancy from an ongoing prospective cohort study and from the community. The mothers and their term, appropriate for gestational age (AGA), healthy infants were seen at 2 weeks and 3months of age. Anthropometrics and body composition (fat mass, fat-free mass, and body fat percent) via air-displacement plethysmography were measured. Infant feeding information was collected. Maternal pre-pregnancy weight was collected via self-report and pregnancy glucose load results were obtained from the medical record. Results were analyzed by multiple-regression analysis controlling for known covariates that affect infant growth and body composition Results: Ninety-seven women/ infant pairs completed both study visits. Pre-pregnancy, 59 mothers were normal weight (BMI 18.5-24.99 kg/m2), 18 were overweight (BMI 25-29.99 kg/m2), and 20 were obese (BMI30.00 kg/m2). At 2 weeks of age, infants did not differ in weight, length, fat free mass, fat mass, or body fat percent across maternal BMI groups. However, by 3 months of age, infants born to mothers with overweight or obese pre-pregnancy BMI had gained less weight, grew less in length, had a smaller increase in head circumference, and had smaller increases in body fat mass and body fat percentage (p= 0.01, 0.003, 0.005, 0.01, 0.01, respectively). The three groups had a similar gain in fat free mass. Including maternal pregnancy glucose values and breastfeeding status in the models did not influence the outcomes. Conclusions: Pre-pregnancy overweight and obesity were associated with reduced early infant linear growth and reduced accumulation of body fat mass, with preservation of increase in lean body mass. This “catch down” in growth and fat mass is a novel finding and may have implications for understanding infant growth, especially in the context of future metabolic risk.