Paternal BMI in the preconception period, and the association with child zBMI

BackgroundRapid growth and excess weight in early childhood are associated with obesity risk. While maternal preconception BMI has been identified as a potential risk factor, the role of paternal preconception BMI is less clear.ObjectivesTo examine the association between paternal preconception BMI and age- and sex-standardized WHO BMI z-score (zBMI) growth rates, zBMI, and weight status, in 0- to 10-year-old children. To determine whether these associations differed by child sex and maternal preconception weight status.MethodsA longitudinal cohort study was conducted through The Applied Research Group for Kids (TARGet Kids!). Children (n = 218) underwent repeated measures of height and weight from birth to 10 years old. Piecewise linear mixed models were used to assess the association between paternal preconception BMI and child zBMI growth rates (zBMI SD units/month) between 0, 4, 30, 48 and 120 months of age. Linear mixed models were used to examine the association with child zBMI, and logistic generalized estimation equations (GEE) were used to assess the association with child weight status. Child sex and maternal preconception weight status were tested as effect modifiers.ResultsPaternal preconception BMI was associated with child zBMI growth rate, mean zBMI and weight status in boys, but not girls. A 5 kg/m2 higher paternal preconception BMI was associated with approximately 0.01 zBMI SD unit/month higher growth rate for boys born to mothers with preconception overweight. Higher paternal BMI was associated with higher mean zBMI and increased odds of overweight and obesity in boys, with greater effects seen when mothers had preconception overweight compared to normal weight.ConclusionPaternal preconception BMI was associated with child zBMI growth rate, zBMI and weight status in boys, with greater effects when the biological mother had preconception overweight or obesity. Further understanding of sex differences in paternal preconception weight effects in children is needed.