35 Hypertension in pregnancy and autism spectrum disorder in a British cohort

Introduction Genetic and environmental influences each have equal weighting in the relative risk for a child of developing ASD. Recently, focal patches of abnormal laminar cytoarchitecture and cortical disorganization of neurons, have been demonstrated in the prefrontal and temporal cortex of children with ASD. This is suggestive of a probable dysregulation cortical lamination which occurs in the 2–3rd trimester of pregnancy, and implies that in utero adversity may disrupt the normal neurodevelopmental program and increase a child's risk of later developing ASD. Recent evidence indicates that pre-eclampsia may be one of these factors. Objectives Our objective was to assess the association between hypertension in pregnancy (HIP), including pre-eclampsia, and ASD among 7 year old children. Methods For this investigation, we utilized data from the Millennium Cohort Study, a cohort representative of children born in the UK in the year 2000–2001. Mothers were asked if they experienced any illnesses during pregnancy for which they needed medical attention. Those that responded yes were asked to choose which illnesses they suffered from, including "raised blood pressure, eclampsia/pre-eclampsia or toxaemia." ASD was parent-reported based on a diagnosis by a doctor or health care professional. We measured the association between HIP and ASD using weighted logistic regression, and adjusted for smoking during pregnancy, birth order, poverty, maternal ethnicity, age, education, depression, BMI, longstanding hypertension and diabetes. Results We included data from 13,098 people who responded to the question on health during pregnancy and ASD. There were 983 (7.5%) reported HIP cases and 199 reported ASD cases (1.5%). HIP was associated with ASD in both unadjusted (OR=2.27; [95%CI: 1.43–3.60]) and adjusted analysis (OR=2.10; [95%CI: 1.20–3.70]). When women who reported longstanding hypertension were excluded, HIP remained associated with ASD (adjusted OR=2.02; [95%CI: 1.12–3.63]). When women aged 40+ at the time of birth were excluded, the estimate increased slightly, but was not significantly changed (adjusted OR=2.63; [95%CI: 1.27–4.02]). Conclusion Hypertension in pregnancy was associated with ASD in this population even after controlling for known confounders. It is increasingly recognized that placental health and neurodevelopmental outcome are intrinsically linked. This raises the possibility of using clinical data regarding the clinical course of pregnancy and the molecular characteristics of the placenta at birth to predict a child risk of future ASD.