Impact of parental weight status on children’s body mass index in early life: evidence from a Chinese cohort

OBJECTIVES: To understand whether parents’ weight status before conception predicts body mass index (BMI) of their offspring in early life and the differences between the mother–child and father–child associations. DESIGN: A birth cohort study. SETTING: Conducted at the Community Health Service Centre in Shenyang, Wuhan and Guangzhou. PARTICIPANTS: A total of 2220 live birth newborns were recruited randomly after consent of their parents, and 1178 were followed up until 2 years old. METHODS: Parental demographics, maternal characteristics during pregnancy, children’s anthropometric data and feeding patterns at 1 month old were collected. BMI was calculated and BMI Z-scores (BMI_Z) were generated by referring to WHO growth standard. Parental weight status was categorised into underweight, normal weight, and overweight and obese according to the Working Group of Obesity in China. General linear models and generalised linear models were used to assess the associations between parents and offspring. OUTCOME MEASURES: The primary outcomes were descriptive data on child’s sex-specific anthropometric variables. The secondary outcomes were BMI_Z and weight status of children at each time point. RESULTS: No gender difference was observed in BMI_Z or overweight or obesity rates from birth to 24 months old, although boys were significantly heavier and had a greater length/height than girls (P<0.05). The overweight and obesity rates of children peaked at 12 months old. Maternal BMI/weight status had a significant but small effect on BMI_Z at birth, but not on the paternal side. The impact of parental BMI on child’s BMI_Z after birth was similar at each follow-up. Offspring with underweight mothers tend to have reduced BMI_Z after birth while overweight/obese fathers had children with a greater BMI_Z. CONCLUSIONS: Maternal weight status had small effect on both fetal and child growth after birth. Significant but mild paternal influence was only detected after birth.