A common fertility treatment used in New Zealand carries a one-in-10 risk of the baby having abnormalities, according to a major international study.
Researchers from the University of Adelaide compared the risk of defects posed by common therapies, including IVF (in vitro fertilisation) and ICSI (intracytoplasmic sperm injection).
About 10 per cent of couples using ICSI were found to have a baby with abnormalities - such as bowel and urinary tract problems, heart and lung conditions and cerebral palsy - making it the riskiest treatment. This compared with IVF, which has a risk of 7.2 per cent.
The procedure, which involves injecting a single sperm into an egg, is used in the public and the private sector.
At least 1600 cycles of ICSI are carried out in New Zealand each year, 800 in Auckland. That mirrors numbers for IVF, said Royal Australian and New Zealand College of Obstetrics and Gynaecology spokeswoman Emma Parry.
When a man's sperm quality was low, ICSI was often the preferred treatment because it had a greater chance of success than IVF.
"Women receive two publicly funded cycles of fertility treatment. So these days what they'd do is identify which couples are going to have problems with standard IVF before they start, and if they are, flick them through to ICSI.
"I think that for most couples that are at the point of going for IVF or ICSI as an option to get pregnant, when faced with this data most of them would still want to continue on that pathway."
The 16-year study included more than 300,000 births in South Australia and followed the children's development for five years. Of those, 6100 were assisted births and 18,000 of the babies were found to have birth defects.
It confirmed previous studies that the risk of birth defects was higher, 8 per cent, compared with natural conception, 6 per cent.