Adriëtte Oostvogels

6 Introduction In 2014, more than half of the women in the United States started their pregnancy with overweight or obesity. 1 This has not only consequences for the health of these women and their pregnancies, but also for the health of their children as children born to overweight and obese women are more often overweight and obese themselves, 2,3 and have an increased risk for cardiometabolic diseases at adult age. 4,5 Although the association of maternal prepregnancy body mass index (pBMI) with offspring’s anthropometrics at certain ages is well studied, 6-8 the impact of maternal weight status on offspring’s growth patterns with serial measurements of weight, height and BMI is less studied. One study in 912 children showed that children of obese mothers had a higher BMI from up to 3.5 years. 9 This study did not examine growth patterns in height and weight from BMI separately. However, growth studies show that both relative weight gain and linear growth are, independent from BMI, important features for optimal growth and independently associated with increased fat mass, fat free mass and systolic blood pressure in children and adults. 10-12 More insight in weight and height growth patterns, might make it possible to identify if the higher BMI growth patterns in children of obese mothers are the result of faster weight gain or slower height gain. Furthermore, to the best of our knowledge, no study has described sex-specific effects of maternal overweight and obesity on offspring’s growth patterns. In the current literature, there is emerging evidence to suggest sex-specific responses to early life hormonal and nutritional exposures. 13 For example Krishnaveni and co- workers showed that girls, but not boys, from diabetic mothers were more adipose at the age of 9 years compared to controls. 14 In addition, girls of overweight mothers might grow faster in height compared to boys, because overweight mothers more often formula-feed than breastfeed, 15-17 and formula-fed girls had higher length gain than breastfed girls, but no differences were observed in boys. 18 This study utilizes repeated longitudinal measurements of height and weight of children from birth up to 7 years to study the influence of maternal prepregnancy weight status on growth patterns of weight, height and BMI across the entire infancy and childhood period. This study extends previous research by separating weight and height growth patterns on maternal weight status, next to BMI alone and by investigating this in boys and girls separately. 149 pBMI and offspring’s growth patterns