Nutritional influences in pregnancy and postpartum for women and their children

Research Doctorate - Doctor of Philosophy (PhD)Maternal factors prior to conception and during pregnancy may influence the development of the metabolic, cardiovascular and endocrine systems of the offspring and subsequent disease pathogenesis. This thesis explores the concept of the developmental origins of health and disease. Human observational research studies were undertaken to test the relationships amongst maternal dietary intake, weight gain during pregnancy and changes in biochemical markers between pregnancy and postpartum for the mother and infant. This thesis presents three chapters of original research related to maternal and fetal nutrition, and one chapter of empirical data concerning the methodological challenges faced when recruiting for research purposes. An analysis of dietary intake data from the young cohort of the Australian Longitudinal Study on Women’s Health was used to determine the overall diet quality in a contemporary cohort, and to assess whether those who are pregnant eat differently to those who are not. Only small differences in diet quality and nutrient intakes were detected between pregnancy groups, and diet quality scores were consistently low. When the intake data were compared to Australian recommendations it appears that many young women fail to reach key nutrient targets, including those set for folate, fibre, calcium, iron, potassium and vitamin E. The research focus then shifted to prospective longitudinal data collection for women and their children during pregnancy and after birth. Low recruitment to this component of the studies threatened the potential to achieve the research aims. Rather than jeopardising the power of the investigations efforts were made to understand what had gone wrong and how the situation could be rectified. An investigation of the relationship between fetal adiposity and maternal weight changes in pregnancy was performed. Pre-pregnancy body mass index (BMI) and weight changes during pregnancy were taken as broad markers of maternal nutritional status and energy regulation. Intrauterine growth, including the accumulation of adipose tissue, was assessed using serial ultrasounds. Fetal size was positively related to maternal pre-pregnancy weight (and BMI) and weight gain (change in BMI) during pregnancy. Maternal pre-pregnancy weight was positively associated with adiposity at the fetal abdomen, but not the thigh. However, overall maternal weight gain was not associated with fetal adiposity. To determine whether maternal vitamin B12 and folate (methyl donors) in pregnancy could influence the offspring’s homocysteine metabolism at birth, changes in plasma vitamin B12, plasma folate and red cell folate were characterised for the cohort of more than 100 women during pregnancy and up to six months after birth. A small sub-sample of infants also had blood collected at six months postpartum. Average maternal plasma folate during pregnancy was significantly predictive of infant plasma homocysteine. In conclusion, the research outlined herein demonstrates important interactions between the mother and her offspring during the critical windows of early development. The research is multidisciplinary in its application and contributes to our understanding of some of the nutritional influences in pregnancy and postpartum for women and their children