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

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Excessive early childhood adiposity is a prevalent and increasing concern in many parts of the world. Parental obesity is one of the several factors previously associated with infant and early childhood weight, length and adiposity. Parental obesity represents a surrogate marker of the complex interplay among genetic, epigenetic and shared environmental factors, and is potentially modifiable. The relative contributions of maternal and paternal body mass index (BMI) to infant and early childhood growth, as well as the timing of such effects, have not been firmly established. WHAT THIS STUDY ADDS: Utilizing serial infant measurements and growth curve modelling, this is the largest study to fully characterize and formally compare associations between maternal and paternal BMI and offspring growth across the entire infancy and early childhood period. Maternal obesity is a stronger determinant of offspring BMI than paternal obesity at birth and from 2 to 3 years of age, suggesting that prevention efforts focused particularly on maternal lifestyle and BMI may be important in reducing excess infant BMI. The observation that maternal BMI effects are not constant, but rather present at birth, wane and re-emerge during late infancy, suggests that there is a window of opportunity in early infancy when targeted interventions on children of obese mothers may be most effective. 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.