Adriëtte Oostvogels

9 cause structural changes in the arcuate nucleus of the hypothalamus, 70 an important structure related to the regulation of energy homeostasis and appetite control. 71 This could cause impaired leptin signaling and leptin resistance 72,73 which, in turn, results in overeating and increased weight/height growth and obesity later in life. 74,75 Overnutrition in both prenatal and postnatal life No human studies have combined the effects of maternal pBMI and accelerated postnatal growth on cardiometabolic profile in childhood in one investigation. In this thesis, significant interaction terms were found between maternal pBMI and postnatal growth, with the highest waist-to-height ratio, systolic blood pressure, triglycerides and metabolic score, in children with the combination of high maternal pBMI and accelerated growth. Similar results were found in animal studies: both pre- and postnatal overnutrition aggravated the effect of postnatal overnutrition alone. 76-78 This appeared to be mainly the result of dysfunctioning adipocytes which caused insulin resistance through inflammation and oxidative stress. 77,78 In our study, the combination of high maternal pBMI and accelerated postnatal weight-for- length gain resulted in the highest levels of triglycerides in childhood. High levels of triglycerides might indicate some form of insulin resistance, especially when accompanied by low HDL-cholesterol, 79,80 which could, therefore, be the result of dysfunctioning adipocytes. Ethnic and socioeconomic inequalities in growth to overweight Both a high maternal pBMI and accelerated postnatal growth of the offspring are more frequent in children of ethnic minority groups and from a low socioeconomic background. 15,81-84 This combination increases the risk for childhood overweight and an adverse cardiometabolic profile. 23-29,46-55 However, since no ethnic inequalities were found in growth to overweight, this suggests that ethnic inequalities in the growth patterns found in other studies (e.g. accelerated growth in the first year) might simply be a reflection of the higher prevalence of overweight in these groups 85-88 rather than an ethnic-specific growth pattern. The socioeconomic inequalities in growth to overweight, as reported in this thesis, have not been described before. However, the socioeconomic inequalities found in growth patterns of overweight mimic socioeconomic inequalities in growth patterns of all children. Children in the high socioeconomic group also had a higher BMI during the first 2 years, 89,90 but a lower BMI later in childhood. 89,91 These inequalities might be attributable to parents’ health-related behaviours, as children of low socioeconomic background are (on average) born with a lower birth weight, 92,93 which could be the result of the high 229 General discussion