HRB Centre for Health and Diet Research

Cluster 2 Diet, obesity and health in pregnancy and childhood

Overview

Birth weight has increased in Ireland over the past 30 years (Mahony 2003) and mothers are now 10kg heavier in pregnancy than 20 years ago. The increasing birth weight seen in Ireland in recent decades is a potential cause for concern, not only because of its association with increased instrumental delivery and perineal trauma, but also because of the association between birth weight and childhood obesity.

Maternal weight and maternal weight gain during pregnancy exert an important influence on infant birth weight. Specifically, it is hypothesised that eating primarily high glycaemic index carbohydrate during pregnancy results in feto-placental overgrowth, excessive maternal weight gain and predisposition to foetal macrosomia (birth weight >4.0Kg). It also hypothesised that altering the source of maternal dietary carbohydrate may prove to be valuable in the management of pregnancies where there has been a history of fetal macrosomia. However, the observational data in support of this hypothesis are sparse and there are no data from well designed randomised controlled trials.

Objectives

The primary objective for this research cluster is to study the effects of maternal diet during pregnancy on fetal growth and risk of obesity in childhood.  Specific hypotheses on the effect of maternal dietary glycaemic index during pregnancy on fetal growth and risk of childhood obesity will be addressed in two interlinked studies:  an observational study and a randomised controlled trial (Projects A and B). In a subsidiary project linked to this cluster we will develop and extend a publicly available database on food composition tables for use in nutritional assessment of Ireland’s immigrant populations (Project C).

Progress to Date

As stated above, specific hypotheses on the effect of maternal dietary glycaemic index during pregnancy on fetal growth and risk of childhood obesity are being addressed in two interlinked studies:  an observational study and a randomised controlled trial. The randomised controlled trial has completed recruitment and the last study baby will be delivered by August 2011. Significant outputs from this study have already been published and include detailed assessment of maternal macro and micronutrient intakes during pregnancy. These data have informed a HSE published paper on the recommendations for nutritional intake in pregnancy in Ireland.  Additional funding has been sought and obtained and Prof McAuliffe is a co-PI in a current FP7 Cooperation ‘Health’ proposal submission on early childhood nutrition.

The Lifeways cross-generation cohort study was established in 2001 and is now in its tenth year of follow-up. It comprises over a thousand families recruited initially through 1124 mothers in two maternity hospitals. All sweeps have been funded by the Health Research Board, including the present collaboration, which has funded a PhD stipend to complete analyses of the dataset collected when children averaged 5 years of age.

The Cluster 2 research team is collaborating with the other clusters on a number of areas including with work with Cluster 3 on the age, period and cohort effects in the distribution of obesity and with Prof Pat Wall in Cluster in 5 who is carrying out qualitative and quantitative analysis of food choices in pregnancy.