Assisted conception, Australia and New Zealand 1999 and 2000

Assisted conception, Australia and New Zealand 1999 and 2000 is the sixth report on the use of assisted reproduction technology (ART) in Australia and New Zealand.

Highlights

• The viable pregnancy rates, those reaching at least 20 weeks' gestation, in 2000 were higher than in any previous year for all IVF and ICSI transfers. When all techniques of assisted conception are included together, the viable pregnancy rate increased gradually from 13.0 per 100 embryo transfer cycles in 1992 to 15.9 in 1999, rising to 17.9 in 2000.
• The number of births after assisted conception in 1999 increased by 11.5% in Australia, and 36.2% in New Zealand, since 1998. There were 4,319 births after assisted conception in Australia in 1999, accounting for 1.7% of all births. In New Zealand, there were 421 births after assisted conception in 1999, accounting for 0.7% of all births.
• Between 1992 and 2000, the total number of cycles with oocyte retrieval or embryo transfer for all techniques of assisted conception increased by 66% from 16,288 in 1992 to 27,067 in 2000. This increase has slowed in recent years, increasing by 1.8% from 26,592 cycles in 1999. There was a relatively greater increase in transfer cycles using frozen embryos than for fresh embryos.
• There has been a marked increase in treatment cycles in which intracytoplasmic sperm injection (ICSI) was used. Oocyte retrieval cycles for ICSI have increased each year from 812 in 1992 to 8,895 in 2000. For the first time, ICSI accounted for more than half (51.4%) of all transfer cycles for all types of assisted conception in 2000.
• The use of gamete intrafallopian transfer (GIFT) for treating infertility has continued to decline sharply, from 3,831 oocyte retrieval cycles in 1992 to 817 cycles in 2000, accounting for only 3.2% (800/24,893) of all transfer cycles in that year. The viable pregnancy rate, 21.4 per 100 oocyte retrieval cycles in 2000, continues to be higher than that for IVF or ICSI.
• In 2000, 16.6% of women seeking assisted conception were aged 40 years or more, increasing from 15.2% in 1999. In 1999, 8.9% of all pregnancies, and 7.0% of all live births, were to women aged 40 or more, compared with 2.3% of all mothers giving birth in Australia, and 2.9% in New Zealand. Increasing maternal age is associated with a poorer pregnancy outcome.
• Between 1997 and 2000, the proportion of IVF and ICSI cycles in which one or two fresh embryos were transferred increased, from 64.9% to 81.2% for IVF and from 66.9% to 77.8% for ICSI. For thawed embryos, the proportion increased from 79.3% to 89.1% for IVF in the same period, and from 82.5% to 89.0% for ICSI. For GIFT, one or two oocytes were transferred in 54.4% of cycles in 2000. Four or more oocytes were transferred in 7.5% of GIFT cycles in 2000. Among pregnancies in 1999, increasing the number of embryos/oocytes transferred was associated with a poorer pregnancy outcome.
• In 1999, multiple pregnancy occurred in 26.8% of GIFT pregnancies, compared with 21.2% for IVF pregnancies and 21.8% for ICSI pregnancies. There was 1 quadruplet pregnancy and 49 sets of triplets among all assisted conception pregnancies.
• In the three-year period 1997-1999, multiple pregnancy for all types of assisted conception occurred in 20.9% of viable pregnancies and varied considerably among the IVF units.