Maternal pre-pregnancy body mass index explains infant's weight and BMI at 14 months: results from a multi-ethnic birth cohort study

Objective: To investigate the association between (self-reported) maternal pre-pregnancy body mass index (pBMI), and child's weight, height and BMI at age 14 months. Design: Prospective multi-ethnic community-based cohort study. Setting: Amsterdam, The Netherlands. Participants: 8266 pregnant women from the Amsterdam Born Children and their Development study, filled out a questionnaire covering socio-demographic data, obstetric history, lifestyle, dietary habits and psychosocial factors, 2 weeks after their first antenatal visit. 7730 gave birth to a viable term singleton infant with information on birth weight, gender and pregnancy duration. Growth data were available for 3171 of these children. Main outcome measures: Weight (g), height (cm) and BMI (kg/m(2)) of the child at age 14 months. Results: pBMI was linearly associated with weight and BMI of the child at age 14 months. One unit increase in pBMI resulted in an increment of 29 g (95% CI 19 to 39) in weight and 0.041 kg/m(2) (95% CI 0.030 to 0.053) in BMI. The effect size decreased after adjustment for birth weight (weight: beta coefficient 19 g, 95% CI 10 to 28; BMI: beta coefficient 0.034 kg/m(2), 95% CI 0.023 to 0.046) and hardly changed after adjustment for all other variables (weight: b coefficient 21 g, 95% CI 11 to 30; BMI: b coefficient 0.031 kg/m(2), 95% CI 0.019 to 0.043). pBMI was not related to height. Conclusions: pBMI is an independent determinant of weight and BMI of the child at age 14 months. At least one third of this effect is mediated through birth weight.