Stronger influence of maternal than paternal obesity on infant and early childhood body mass index: The Fels Longitudinal Study

Background/objective: Parental obesity influences infant body size. To fully characterize their relative effects on infant adiposity, associations between maternal and paternal body mass index (BMI) category (normal: ≤25 kg m-2, overweight: 25-<30 kg m-2, obese: ≥30 kg m-2) and infant BMI were compared in Fels Longitudinal Study participants. Methods: A median of 9 serial weight and length measures from birth to 3.5 years were obtained from 912 European American children born in 1928-2008. Using multivariable mixed effects regression, contributions of maternal vs. paternal BMI status to infant BMI growth curves were evaluated. Cubic spline models also included parental covariates, infant sex, age and birth variables, and interactions with child's age. Results: Infant BMI curves were significantly different across the three maternal BMI categories (Poverall <0.0001), and offspring of obese mothers had greater mean BMI at birth and between 1.5 and 3.5 years than those of over-and normal weight mothers (P ≤ 0.02). Average differences between offspring of obese and normal weight mothers were similar at birth (0.8 kg m-2, P = 0.0009) and between 2 and 3.5 years (0.7-0.8 kg m-2, P <0.0001). Infants of obese fathers also had BMI growth curves distinct from those of normal weight fathers (P = 0.02). Infant BMI was more strongly associated with maternal than paternal obesity overall (P <0.0001); significant differences were observed at birth (1.11 kg m-2, P = 0.006) and from 2 to 3 years (0.62 kg m-2, P3 years = 0.02). Conclusion: At birth and in later infancy, maternal BMI has a stronger influence on BMI growth than paternal BMI, suggesting weight control in reproductive age women may be of particular benefit for preventing excess infant BMI.