Aims:  To determine the effect of increasing maternal body mass index (BMI) during pregnancy on maternal and infant health outcomes.
Methods:  The South Australian Pregnancy Outcome Unit’s population database, 2008 was accessed to determine pregnancy outcomes according to maternal BMI. Women with a normal BMI (18.5–24.9 kg/m2) formed a reference population, to which women in other BMI categories were compared utilising risk ratios and 95% confidence intervals.
Results:  Overweight and obese women had an increased risk of gestational diabetes, hypertension and iatrogenic preterm birth. Labour was more likely to be induced, and the risk of caesarean birth was increased. Infants were more likely to require resuscitation at birth and to have birth weight in excess of 4 kg. The risk increased with increasing maternal BMI.
Conclusions:  There is a well‐documented increased risk of maternal and perinatal health complications for women who are overweight or obese during pregnancy.