London: Infertile men, please note -- fertility jabs may be harmful for your future child, for a new study says they increase the risk of birth defects in kids.
The study by University of Adelaide on more than 300,000 babies found that children conceived through the common method of fertility treatment had a significantly higher risk of developing abnormalities than those conceived naturally.
In fact, babies born as a result of intracytoplasmic sperm injection (ICSI) -- where a single sperm is injected directly into egg -- were more likely to suffer abnormalities, `The Daily Telegraph` reported.
In ICSI, the embryologist injects a single sperm directly through the shell of the egg and depositing it inside. This means that abnormal sperm, which would normally be filtered out by the process, are able to fertilise the egg.
However, researchers were unable to establish whether this was because the ICSI technique itself increases the risks of abnormality or because men suffering from extreme sperm damage were more likely to pass on genetic anomalies.
But the study also found that traditional In-Vitro Fertilisation (IVF) treatment did not increase the risk of birth defects. In IVF treatment the sperm and eggs are mixed together in a dish and the sperm breaks into the egg on its own in order for fertilisation to occur.
The researchers, in fact, examined 308,000 births in South Australia over a period of 18 years.
Prof Michael Davies, the study`s lead author, said: "A history of infertility, either with or without assisted conception, was significantly associated with birth defects.
"While factors associated with the causes of infertility explained the excess risk associated with IVF, the increased risk for a number of other treatments could not readily be explained by patient factors."
The study found the unadjusted risk of a birth defect was 5.8 per cent following natural conception, compared with 7.2 per cent for those following IVF, and 9.9 per cent for those after ICSI, according to `New England Journal of Medicine`.
While there was no significant difference in the risk between IVF and natural conception, once other factors were taken into account, the risks to those born following ICSI remained significantly higher.
The increased risk of major defect with ICSI was 57 per cent, Prof Davies said, although the absolute size of the risk remained relatively small.
Dr Allan Pacey of British Fertility Society said: "The study suggests that whilst babies born from IVF are as healthy as their naturally conceived counterparts, there is still some residual risk to babies born through ICSI that currently cannot be explained."