Prevalences of cardiometabolic disorders and obesity are rapidly increasing. This trend indicates that the probability of reaching the World health organization (WHO) global obesity target, of no rise in obesity by 2025, is close to zero. In 2014, an estimated 41 million children under 5 years of age were affected by overweight or obesity. Thus, also childhood obesity has reached alarming proportions. Growth in early childhood is an important determinant of risk of obesity and adverse cardiometabolic profile in childhood and during the life course. Childhood obesity overlaps with indicators of cardiometabolic disorders, and associates with higher prevalence of comorbidities and higher mortality rates in adulthood. Although, signs of levelling off in some setting, childhood obesity is still increasing in disadvantaged segments of many populations including the Nordic. Thus, there is an urgent need to tackle the development of childhood obesity and to identify prevention strategies to combat childhood obesity and its comorbidities, including cardiometabolic risk profiles. WHO points out, that considerations of exposures in the environment throughout the life-course are required, and that pregnancy is regarded as a critical period in this context. Appetite and long-term regulation of energy balance in the offspring may be permanently programmed by the environment in utero during pregnancy, which may influence lifelong consequences for health. Thus, pregnancy may be crucial for preventive strategies to combat childhood obesity and cardiometabolic disorders and promote health of the next generation. Poor maternal vitamin D status in pregnancy has been identified as a potential modifiable early-life risk factor for prevention of obesity development and adverse cardiometabolic profile. Nevertheless, the evidence of the adverse effects of poor maternal vitamin D status remains insufficient, and the effects on childhood growth beyond infancy are largely unknown. We know though that poor vitamin D status may occur during winter and among those with low vitamin D intake. Additionally, vitamin D deficiency is especially common among ethnic minorities at Northern latitudes. Mother and child cohorts are ideal to study exposure-outcome associations, because of the extensive assessment of socioeconomic, health and lifestyle factors. We aim to test the hypothesis that low maternal vitamin D intake and poor vitamin D status may affect growth and increase the obesity risk throughout childhood, resulting in an unfavorable cardiometabolic profile.Two cohorts will be included
1) the Norwegian Mother, Father and Child Cohort Study (MoBa), with
95 200 women and children to 13/14 years; and 2) the multi-Page 8 of 13 ethnic Swedish Mother- and Child cohort (GraviD-child), with 2125 women and children to 5 years.
The specific aims are to study:1. The association between maternal intake of vitamin D and growth throughout childhood and obesity risk in children (n~80000 mother-child pairs, MoBa). 2. The association between maternal vitamin D status (serum 25-hydroxyvitamin D, 25OHD) and growth in childhood and obesity risk in children (n~3000 mother-child pairs MoBa and n~2000 mother-child pairs GraviD-child).
3. The association between maternal vitamin D status and child cardiometabolic risk profile (n~700 mother-child pairs, MoBa).
4. If associations are observed from the previous aims, we will further explore the biological pathway through which maternal vitamin D status during pregnancy can program later excess weight gain as part of an unfavorable cardiometabolic profile in children by:
i. Studying the hypothesis of an inflammatory pathway that might mediate the association between maternal vitamin D status and growth in childhood and obesity risk in children. ii. Studying the hypothesis of impaired maternal glucose metabolism and stress might mediate the observed association with child´s weight.
