Dietary patterns in pregnancy and offspring growth outcomes: a multi-country analysis of birth cohorts

Fetal life and early childhood are periods of rapid growth and development and both serve as important indicators of health in later life. Maternal diet during pregnancy has been recognised as one of the major lifestyle factors influencing both fetal growth and long term health. The link between maternal dietary patterns and fetal growth has been examined to some extent, little however is known on the potential long term effects on child growth. Using data from three large international cohort studies, this thesis aimed to assess the effect of maternal dietary components and patterns during pregnancy on offspring growth. The literature review revealed a heterogeneous body of studies that was generally supportive of a positive association between a health conscious maternal dietary pattern during pregnancy characterised by high intakes of fruit, vegetables, water and wholegrains and offspring size at birth. The evidence relating later child growth to maternal diet in pregnancy was inconclusive mainly due to a lack of research as well as heterogeneity amongst studies. Analyses of the association between maternal alcohol intake and fatty fish consumption prior to and during pregnancy and offspring size at birth was explored; providing further support on the evidence of alcohol as a teratogen, even in low amounts in the first trimester of pregnancy. The evidence for fatty fish intake however was inconclusive. In order to facilitate between study comparisons, a common food grouping system was applied to dietary data from the three cohorts and principal component analysis was performed on energy adjusted dietary data. Two, four and seven components were derived from each cohort. However, the dietary patterns identified from the different cohorts did share some commonalities. In particular, a dietary pattern characterised by high positive correlations with fruit, water and unrefined grains and negative correlations with refined grains and chips, seemed to be present in all three datasets. These were also the components that showed the most convincing associations with offspring growth outcomes at birth and around 7 years of age, even after taking into account known confounders and assessing possible mediation by birth weight and gestational weight gain as well as effect modification by breastfeeding and maternal pre-pregnancy BMI status.