Adriëtte Oostvogels

9 is known about the underlying mechanisms of sex differences in outcomes due to maternal overnutrition. 102 A possible explanation might be differences in prenatal growth patterns or placental function between boys and girls, which are caused by differences in gene expression in response to maternal metabolic status. 103 Implications for research and public profile Suggestions for future research In the ABCD-study, because no information was available on paternal pBMI, it was not possible to compare the associations of maternal or paternal pBMI with the outcomes reported in this thesis. Had similar associations been found between maternal and paternal pBMI, this might have allowed to conclude that shared environmental or genetic factors explained the associations, instead of a possible intra-uterine factor. 34,35 Until now, some studies found similar associations between both maternal and paternal pBMI, and birth weight, body composition and cardivascular risk factors, 36-40 whereas others found that associations with maternal pBMI were stronger than with paternal BMI. 26,41-43 However, a stronger association with maternal pBMI does not necessarily mean that an intra-uterine effect was present: mothers spend (on average) twice as much time with their children than the fathers. 104,105 Therefore, stronger associations with maternal pBMI may also be due to postnatal influences. In summary, additional research, including data on paternal pBMI, in combination with the father’s contribution to parenting, might further elucidate the role of parental pBMI and the consequences for offspring’s cardiometabolic profile. Moreover, other components of the maternal metabolic profile should also be examined. First, glucose: studies have shown that gestational diabetes mellitus ( GDM) has long-term effects on the offspring. 27,106-109 However, little research has focussed on the impact of parameters of glucose metabolism in women without GDM. Regnault et al. showed that maternal glycaemia did not have a direct effect on birth weight, but this was mediated by foetal insulin and IGF-I. 110 Moreover, cord C-peptide was associated with slower weight gain in girls in the first 3 months. 110 Therefore, it seems worthwhile to examine parameters of maternal glucose metabolism in relation to offspring’s cardiometabolic profile, as glucose values can be kept within the normal range by higher amounts of insulin; this parameter is not measured during standard screening for GDM, but is known to drive foetal growth. 111 Second, blood pressure: hypertensive disorders of pregnancy are associated with increased blood pressure in the offspring. 112-114 Although few associations were found when systolic/diastolic blood pressure at the start of pregnancy was related to offspring’s cardiometabolic 231 General discussion