Maternal preconception weight trajectories are associated with offsprings' childhood obesity.

Objectives: This study aimed to examine the associations between (1) mothers' preconception body mass index (BMI) trajectories over 6-7 years and offspring childhood BMI, and (2) mothers' BMI changes between first and second pregnancy and the second-born child's BMI.
Methods: We used data (1606 mothers with 2733 children with mean age 7.7 years, SD 2.9) from the Australian Longitudinal Study on Women's Health and the Mothers and their Children's Health study. Preconception BMI trajectories were identified using latent class growth modeling. Children were categorized as underweight, normal, overweight or obese based on age and sex-specific BMI cut-off points for children. Multinomial and binary logistic regression were used for analyses.
Results: We identified three preconception BMI trajectories, named as 'normative' (61.2%), 'chronically overweight' (30.7%), and 'chronically obese' (8.1%). Children born to 'chronically overweight' and 'chronically obese' mothers were more likely to be overweight than normal weight relative to children born to women with a 'normative' BMI trajectory. The corresponding adjusted relative risk ratios (RRRs) (95% confidence interval [CI]) of childhood overweight were 1.75 (1.33, 2.31) for chronically overweight mothers and 2.48 (1.65, 3.73) for chronically obese mothers. Similarly, we found a much stronger association between 'chronically overweight' and 'chronically obese' BMI trajectories and childhood risk of obesity; RRR (95% CI), 2.49 (1.41, 4.40) and 6.65 (3.40, 13.01), respectively. Second-born children of mothers with high interpregnancy weight gain (≥4 BMI units) were also at higher risk of being overweight or obese (OR = 2.20, 95% CI: 1.02, 4.75) compared with children of mothers with stable interpregnancy weight (gain or loss of 1 BMI unit or less).
Conclusions: In this population-based prospective cohort study, we found strong dose-response associations between preconception BMI trajectories and offsprings' childhood BMI.