Assisted conception, Australia and New Zealand 1991

Highlights

• Assisted conception by in-vitro fertilization (IVF) and gamete intrafallopian transfer (GIFT) was used to treat infertile couples in 21 units in Australia and 5 in New Zealand in 1991. This treatment resulted in 1,064 live births after IVF and 945 after GIFT in Australia and 63 live births after IVF and 11 after GIFT in New Zealand.
• There were 8,516 IVF treatment cycles commenced in 1991. Of 7,353 treatment cycles commenced for uterine transfer of embryos, 6,588 progressed to the stage of oocyte retrieval and 5,457 to embryo transfer. Of 1,163 treatment cycles commenced for tubal transfer, 1,089 progressed to oocyte retrieval and 840 to embryo transfer. There were 4,372 cycles commenced for GIFT, with 3,830 progressing to oocyte retrieval and 3,758 to embryo transfer. The live-birth pregnancy rates for IVF with uterine transfer, IVF with tubal transfer, and GIFT were 7.8, 9.6, and 19.5 per 100 oocyte retrieval cycles, respectively.
• Embryo freezing was used in 24 of the 26 IVF units in 1991. The live-birth pregnancy rate in 3,207 transfer cycles after embryo freezing and thawing was 10.0 per 100 embryo transfer cycles. The increased use of embryo freezing, which reduces the need for ovarian stimulation in subsequent treatment cycles, resulted in an increase in the number of frozen embryos in storage from 13,016 in 1991 to 19,893 in 1992.
• In 293 IVF cycles with donor oocytes, the live-birth pregnancy rate was 9.2 per 100 embryo transfer cycles. There were also 28 oocyte retrieval cycles for combined IVF and GIFT, 328 cycles with sperm microinjection, 40 cycles with sperm retrieval, and 25 cycles with zona drilling or cutting.
• Treatment by assisted conception in Australia increased from 428 to 549 cycles per 100,000 women aged 25-44 years between 1990 and 1991. In the same period, the increase in New Zealand was from 93 to 102 cycles per 100,000 women. The treatment ratios in Australian States with more than one IVF unit ranged from 680 per 100,000 women in Victoria to 353 per 100,000 women in Western Australia. The relative use of fresh embryo transfer, frozen embryo transfer and GIFT also varied among the States.
• Multiple pregnancies after IVF decreased from 21.2% in 1990 to 16.0% in 1991, the twin rate declining to 14.4% and the triplet rate to 1.5%. There were no quadruplet births after IVF in 1991. This decline in multiple births after IVF was due to a reduction in the number of embryos transferred.
• The decline in multiple pregnancies after GIFT was less pronounced than after IVF. The twin rate decreased from 22.6% in 1990 to 21.7% in 1991 and the triplet rate from 4.3% in 1990 to 3.4% in 1991. There were also 1 quadruplet and 1 quintuplet pregnancies in 1991. The proportion of GIFT pregnancies that resulted from transfer of 4 or more oocytes increased from 7.8% in 1990 to 9.8% in 1991.
• The perinatal mortality rates of 31.4 per 1,000 births after IVF and 36.8 per 1,000 births after GIFT in 1991 were lower than in previous years. Multiple births accounted for more than half of all perinatal deaths in the total period between 1979 and 1991, 50.5% after IVF and 70.2% after GIFT.
• In the same period, major congenital malformations occurred in 2.4% of births and induced abortions after IVF and in 2.7% after GIFT.