Comparison of associations of maternal peri-pregnancy and paternal anthropometrics with child anthropometrics from birth through age 7 y assessed in the Danish National Birth Cohort

Background: Maternal pre-pregnancy adiposity may influence child adiposity beyond the transmitted genetic effects, which, if true, may accelerate the obesity epidemic, but the evidence for this mechanism is inconsistent.
Objective: To assess whether the associations of maternal body mass index (BMI; weight/height2 kg/m2) with child anthropometrics from birth, through infancy and at 7 years of age exceed those of paternal associations.
Design and analyses: In the Danish National Birth Cohort, information on parental and child anthropometrics is available for 30,655 trio families from maternal interviews during pregnancy and the postpartum period and from a 7 year follow-up. Using multiple linear and logistic regression models of child standard deviation (z)-scores of weight and BMI at birth, 5 months, 12 months, and 7 years, and of child overweight at age 7 years, we compared associations with maternal pre- pregnancy and post-partum BMI z-scores and with paternal BMI z-scores.
Results: Comparing maternal-child and paternal-child BMI z-score associations, strongest associations were observed with mothers’ BMI at birth (0.143 (95% CI: 0.130,0.155) per maternal BMI z-score, and 0.017 BMI z-scores (CI: 0.005,0.029) per paternal BMI z-score), and throughout infancy, but the relative difference in the associations declined by child age (for BMI z-score at child age 7 years: 0.208 (CI: 0.196,0.220) per maternal BMI z-score, and 0.154 (CI: 0.143,0.166) per paternal BMI z-score). At 7 years of age the odds ratios of child overweight were 2.30 (CI: 1.99,
2.67) by maternal overweight and 1.96 (CI: 1.74, 2.21) by paternal overweight. There were no differences between the results based on maternal BMI before and after pregnancy or on children’s weight adjusted for length or height.
Conclusion: The associations of child weight and BMI with maternal BMI were stronger than with paternal BMI. Associations between maternal and child anthropometrics were strong at birth, but declined with child ageing.