Twin deliveries and place of birth in NSW 2001-2005

Twin pregnancies have an elevated risk of adverse outcomes, particularly preterm twins.

Describe the distribution of twin deliveries by hospital level, the associated perinatal and maternal morbidity, and determine predictors of perinatal morbidity and urgent transfer to a neonatal intensive care unit.

Longitudinally linked New South Wales delivery and hospital records for the years 2001-2005 were used to identify perinatal and maternal morbidity/mortality in twin pregnancies. Regression analysis was used to examine predictive factors, including birth hospital volume.

At < or = 32 weeks, 88.1% of twins were delivered in tertiary referral hospitals. By 34-35 weeks, only 39.7% of twins were delivered in tertiary units. Gestational age was the primary predictor of perinatal morbidity/mortality. Perinatal morbidity/mortality and maternal morbidity were lowest for deliveries at 38 weeks. There was no evidence that planned caesarean section at < or = 38 weeks was protective against perinatal morbidity/mortality. There was an increased risk of perinatal morbidity/mortality (odds ratio (OR) = 2.22) for twins delivered at 33-35 weeks gestation at hospitals with < 500 deliveries per annum, and an increased risk of urgent neonatal transfer (OR = 2.06). Twin pairs for whom there was a > or = 20% discordance in birthweight had an increased risk of morbidity/mortality at 36-38 weeks (OR = 1.79).

Both infant and maternal morbidity increase from 39 weeks gestation. Delivery of twins before 36 weeks at smaller hospitals (< 500 deliveries per annum) should be avoided. A twin pregnancy where there is a > or = 20% difference in estimated fetal weights should be considered for referral to a tertiary obstetric unit.