Abstract
Objective. We investigated how average weekly gestational weight gain rates during three periods of pregnancy were related to the offspring's body mass index (BMI) at 7 years of age. Methods. We used data from the Danish National Birth Cohort. Information from pregnancy interviews conducted between week 12–20 (Interview 1) and week 25–32 (Interview 2) was used to calculate maternal weight gain in the following periods: up until Interview 1; between Interview 1 and 2; from Interview 2 until delivery. Life Course Path Analyses were used to obtain effect estimates of the rates of gain on the offspring's BMI. Results. Average weekly gestational weight gain rates in first and second period of pregnancy were significantly associated with the child's BMI (ß-coefficient (95% CI): 0.049 z-score/z-score (0.030, 0.067), and 0.059 z-score/z-score (0.041, 0.077), respectively). No significant association between weight gain in the third period and the child's BMI was found (ß-coefficient (95% CI): 0.016 z-score/z-score (−0.002, 0.034)). The total effect estimate from the third period was furthermore significantly lower than the effect estimates from the first and second period (p < 0.03 and p < 0.002, respectively). Conclusion. Gestational weight gain in first and second, but not in the last period of pregnancy were positively associated with the offspring's BMI at 7 years of age, even though the estimates were small. Fetal environmental factors may influence the unborn child differently depending on timing of exposure. Therefore, it may be important to consider the different fetal developmental stages when linking early life experiences with later health.
Acknowledgements
The Danish National Research Foundation donated a major grant and established the Danish Epidemiology Science Centre that created the DNBC. Additional support was obtained from the Pharmacy Foundation, the Egmont Foundation, the March of Dimes Birth Defects Foundation, the Augustinus Foundation, and the Health Foundation. The 7-year follow-up received financial support from the Lundbeck Foundation (195/04) and the Danish Medical Research Council (SSVF 0646). This study is part of the Danish Obesity Research Centre (see http://www.danorc.dk/) and has been supported by Lundbeck Foundation (267/06), The Danish Graduate School in Public Health Science, and The Danish Agency for Science, Technology and Innovation (271-06-0421).
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.