BABIES conceived through certain fertility treatment techniques are about one-third more likely to have a birth defect than babies conceived without any extra help from technology, according to a review of several dozen studies.
However, the researchers -- whose findings were published in the journal Fertility and Sterility -- did not determine why fertility treatments are tied to a higher risk of birth defects or whether the technology is even responsible.
In vitro fertilisation (IVF) -- in which the mother's egg is fertilised outside of her body and then transferred to her womb -- has been available to would-be mothers for more than three decades, and numerous studies have looked at the potential hazards of these techniques.
Zhibin Hu at Nanjing Medical University and colleagues collected the results of 46 studies that compared the number of birth defects among children conceived using an IVF technique to children conceived normally.
For more than 124,000 children born through IVF or using ICSI, in which a single sperm is injected directly into the egg, the risk of having a birth defect was 37pc higher than that of the other children, they found.
"Children conceived by IVF and/or ICSI are at significantly increased risk for birth defects, and there is no risk difference between children conceived by IVF and/or ICSI," the team wrote.
"(The report) confirms what most people accepted anyway, that, yes, there is an increased risk in congenital abnormality associated with assisted reproductive technology," said William Buckett, a professor at McGill University, who was not involved with the review.
The increase in birth defect risk was apparent across a range of functions and body systems, including the genitals, skeleton, digestive system and the nervous system, the authors reported.
It's possible that the IVF techniques themselves, the jostling and handling of the embryos, or the drugs that go along with fertility treatment, could be involved.