The effects of post-term birth, hyperemesis gravidarum, and birth order on childhood metabolism and body composition

Abstract

Background: There is increasing evidence that early life events have major implications for health in later life. For example, studies at Liggins Institute have shown adverse metabolic outcomes in children and adults born small-for-gestational-age or preterm. In this thesis, glucose homeostasis and body composition (amongst other assessments) were evaluated in three under-explored groups of children, i.e. those i) born post-term (≥42 weeks gestation), ii) born of mothers who suffered from severe hyperemesis gravidarum, and iii) first-borns. Participants: Healthy pre-pubertal children, aged 4–11 years, naturally conceived, born of singleton pregnancies and of birth weight appropriate-for-gestational-age (birth weight >-2 and <2 standard deviation scores), recruited in Auckland, New Zealand. Methods: Primary outcome was insulin sensitivity measured using intravenous glucose tolerance tests and Bergman’s minimal model. Other assessments included body composition from wholebody dual-energy X-ray absorptiometry, fasting hormonal concentrations and lipid profiles, 24-hour ambulatory blood pressure monitoring, and inflammatory markers. Results: We found that i) post-term children had a 34% reduction in insulin sensitivity in comparison to controls born at term, and also displayed a number of early markers of the metabolic syndrome; ii) children born to mothers who experienced severe hyperemesis gravidarum had insulin sensitivity that was 20% lower than that of controls; and iii) although first-born children were taller and slimmer, these children had a 27% reduction in insulin sensitivity and higher daytime blood pressure compared to later-borns. Conclusions: We have identified three common groups of children (those born post-term, born of mothers who suffered from hyperemesis gravidarum, and first-borns) who are likely to be at an increased risk of developing type 2 diabetes mellitus and other metabolic and cardiovascular diseases later in life. Therefore, long-term follow up of these groups into adulthood is important, so that potential long-term adverse health effects can be better evaluated.