The wider perinatal significance of the Australian in vitro fertilization data collection program.

The most recent report (1986) from the Australian Register of In Vitro Fertilization pregnancies comprises 2242 in vitro fertilization (IVF) pregnancies and 261 gamete intrafallopian transfer (GIFT) pregnancies. A review of this data base indicated that this population had a relatively high incidence of both obstetric and perinatal morbidity and perinatal mortality. About 58% of the IVF pregnancies resulted in live births and 36.4% of the infants weighted less than 2500 gm at birth. These high rates could be partially accounted for by maternal prepregnancy risk factors, such as age, and by risk factors associated with the infertility management, such as multiple pregnancy (22% of all pregnancies more than 20 weeks), which accounted for approximately 50% of the preterm births (less than 37 weeks). Singleton pregnancies also had a higher incidence of preterm birth (17.8% at gestational age 24 to 36 weeks), low-birthweight babies (15.9% less than 2500 g) and perinatal mortality rates (35.4% per 1000 live births) than the Australian population at large. This warrants these patients being regarded as high risk. It is reassuring that the incidence of major malformations in IVF births (2.2%) is similar to that in the general population (1.4%).