Twin Babies from IVF Falling.
The number of twins born to IVF mums is plummeting as more women opt to have just a single embryo implanted to fall pregnant, official fertility figures show.
A trans-Tasman report into assisted reproductive technology (ART) shows that fertility specialists are encouraging women to avoid a double embryo transfer.
Implanting two embryos slightly increases the chance of pregnancy but is more likely to result in twins, which are more likely to be born underweight and premature and with a higher risk of birth defects than singleton babies.
New statistics released by the Australian Institute of Health and Welfare (AIHW) show that almost half - 48 per cent - of all ART treatment cycles in Australia and New Zealand are now single-embryo transfers, compared with 28 per cent in 2002.
As a result, the number of twins born has dropped from more than 40 per cent of ART births in 2002 to 23 per cent in 2005.
Fertility expert and AIHW adviser Professor Michael Chapman said these figures could be expected to shrink to just 10 per cent in the next five years as more fertility experts and parents opted for single embryo procedures.
"The end result of this is bigger babies, healthier babies, so it is great to see these numbers dropping so fast," Prof Chapman said.
"I think specialists who are advising parents have been won over to the notion that twins are a bad thing."
Since 2002, the Fertility Society of Australia has recommended that women under 35 have only one embryo implanted. But the single embryo option remains less popular among older women, who are most keen to have a first-time pregnancy success.
The AIHW report, called Assisted Reproduction Technology in Australia and New Zealand 2005, counted 51,017 treatment cycles in Australia and New Zealand in 2005, including 3,356 donor sperm insemination cycles.
The number of ART babies born in the two countries soared from 6,792 in 2004 to 9,764 in 2005, with such births now accounting for almost three per cent of Australia's annual birthrate.
The average age of IVF mums was 35.5 years, slightly higher than the previous year. The proportion over 40 also increased fractionally to 15.3 per cent.
The death rate among IVF babies dropped by a quarter between 2004 and 2005, largely due to the increase in safer single embryo transfers and singleton births.
Only eight per cent of babies born from a single embryo procedure had a low birth weight, compared with 25 per cent of babies born after two embryos were implanted.
The results are in line with a study presented at the national fertility conference in Hobart last month showing IVF twins were a vastly bigger cost to the health system.
A twin delivery cost $24,000, due to clinical complications and post-birth care, compared with $8,000 for a solo IVF baby.
This is interesting as we have been told we will only transfer one, and I was a bit flat about it reducing our chances (or in the very least, meaning we may need more cycles before success). Good to know we aren't alone in the single transfer stakes.