Design, setting and participants: Retrospective 12-year cohort study of 75 432 women with singleton pregnancies who had pre-pregnancy height and weight data available and who gave birth in a tertiary referral maternity hospital in Brisbane between January 1998 and December 2009.
Main outcome measures: Maternal body mass index (BMI); prevalence of overweight and obesity, and pregnancy complications including hypertension, gestational diabetes, caesarean delivery, and perinatal morbidity and mortality.
Results: From 1998 to 2009, class III and class II obesity increased significantly (from 1.2% to 2.0%, and 2.5% to 3.2%, respectively), while the proportions of underweight women and those with class I obesity fell slightly (from 7.9% to 7.4%, and 7.7% to 7.5%, respectively). Increasing maternal BMI was associated with many adverse pregnancy outcomes, including hypertension in pregnancy, gestational diabetes, caesarean delivery, perinatal mortality (stillbirth and neonatal death), babies who were large for gestational age, and neonatal morbidities including hypoglycaemia, jaundice, respiratory distress and the need for neonatal intensive care (P < 0.001 for all). Most associations remained significant after adjusting for maternal age, parity, insurance status, smoking status, ethnicity and year of the birth. The frequency of congenital anomalies was not associated with maternal BMI (P = 0.71).
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