Pre-pregnancy obesity, pre-existing diabetes, and the risks of serious adverse fetal outcomes

Abstract

The epidemics of obesity and diabetes are two of the leading threats to health in the 21st century. Maternal obesity complicates a large and increasing minority of pregnancies, and pre-existing diabetes is one of the most common maternal chronic health complications of pregnancy. This Doctoral Statement presents a portfolio of six published articles that draw on the North of England’s long-standing population-based registries of maternal and perinatal health to investigate the effects of pre-pregnancy obesity and diabetes on a range of serious adverse pregnancy outcomes. The first two articles examined a cohort of pregnant women who delivered in five of the region’s hospitals during 2003-2005 to explore the associations between maternal body mass index and the risks of, 1) congenital anomaly and 2) fetal and infant death. The next three examined a cohort of pregnant women with pre-existing diabetes who delivered during 1996-2008 to explore the effects of the condition on, 1) congenital anomaly, 2) birth weight, and 3) fetal and infant death. The final article examined women with pre-existing diabetes who had delivered two successive pregnancies to explore the influences of recurrent adverse pregnancy outcome. Maternal pre-pregnancy obesity and diabetes were both associated with increased risks of congenital anomaly, stillbirth, and infant death, with stronger effects for diabetes than obesity. In diabetes, peri-conception glycaemic control was strongly associated with birthweight and the risks of congenital anomaly, stillbirth, and infant death, and previous adverse outcome was associated with a doubled risk in the second pregnancy. For each article I provide a contemporary analysis of its contribution to the literature and critique of the methodology. The wider relevance of the research is also considered by discussing the evidence for causality, potential mechanisms, and implications for public health. Finally, I reflect on my individual contributions and my development towards an independent epidemiologist.