Objective: To examine higher order multiple pregnancy and birth rates in NSW, and to describe trends in the characteristics and management of these births.
Design: Cross-sectional analytic study.
Setting: New South Wales, Australia.
Population: Two hundred and ninety-one women who gave birth to triplets, quadruplets or quintuplets (880 babies) from 1 January 1990 to 31 December 1999.
Methods: Data were obtained from the NSW Midwives Data Collection and rates over time were calculated.
Main outcome measures: Higher order multiple birth and pregnancy rates (> or = 20 weeks), place of birth, mode of delivery, fetal death rates and Apgar scores.
Results: There was no significant change in the number or rate of higher order multiple births in NSW during the 1990s with an average annual rate of 10.3/10,000 births or 3.5/10,000 pregnancies > or = 20 weeks. Among women with higher order multiple pregnancies, those aged > or = 35 years increased from 19% in 1990 to 47% in 1999. There was also a trend towards delivery in a perinatal centre from 56% to 70%, and vaginal birth from 18% to 28%. There were no significant changes in infant outcomes.
Conclusions: The increases in higher order multiple pregnancies observed in Australia in the 1980s, and into the 1990s in other countries, have not persisted in NSW, suggesting that guidelines for limiting the number of embryos/oocytes transferred in assisted reproductive technologies have been widely adopted.