Are IVF babies at greater risk of birth defects?

For couples considering IVF, new research suggesting that it could be to blame for a rise in birth defects over the last 25 years might give pause for thought. The study, published last week in the British Journal of Obstetrics and Gynaecology, had two crucial - and related - findings. The first was that in 14 countries across Europe there was a 50% rise in the number of multiple births between 1984 and 2007, most of which were ascribed by researchers to the increasing use of hi-tech fertility treatments. Secondly, in the same period, the rate of birth defects among these babies almost doubled, from 5.9 to 10.7 per 10,000 births.

"More research is needed but we suspect that the rise in birth defects among multiple births could be the result of assisted reproduction technology," says Dr Breidge Boyle, one of the study's authors. The types of defects found to have increased were not chromosomal abnormalities (such as Down's syndrome), she says, but physical defects that can develop during pregnancy, notably heart problems and digestive abnormalities.

So should couples contemplating hi-tech fertility treatment think again? Some specialists have been quick to point out that the risk of birth defects found in the study among babies from multiple births was extremely small, with 10 cases per 10,000 equating to 0.1% of all multiple births.

"We are talking about truly tiny numbers here," said a spokesmperson at Bourn Hall Clinic in Cambridge, founded by IVF pioneers Patrick Steptoe and Professor Robert Edwards, who achieved the first IVF baby, Louise Brown, in 1978.

Specialists also say that IVF is now resulting in fewer multiple births, which are associated with premature delivery, low birth weight and serious health problems, including cerebral palsy and behavioural difficulties.

In 2009 the Human Fertilisation and Embryology Authority (HFEA), which regulates fertility treatment in the UK, acted to drive down the number of multiple births. These now account for fewer than one in five of all IVF pregnancies, and are mostly only twin pregnancies.

"We know that multiple births associated with IVF have a risk of complications, including birth defects, although there is little data," says Janine Elson, deputy medical director at the Bridge Centre for fertility treatment, in London. "This study provides further reasons to drive down multiple births and use single embryo transfers [where only one embryo is placed in the womb] where possible."

Whether reducing multiple births also reduces the potential risk of birth defects is a moot point, though. Dr Boyle points out that the problem might be with the process of IVF itself - in which case using single embryos will make little difference to the risk.

One concern being voiced is that while in the past little difference was seen in the rate of birth defects between IVF and naturally conceived pregnancies, the picture now seems to be changing.

In October last year, research on nearly 50,000 infants in the US, presented at a paediatrics conference in New Orleans, found that 9% of babies born with IVF had a birth defect compared with 6.6% of those born naturally.

Dr Gedis Grudzinskas, formerly Emeritus Professor of Obstetrics at Barts and the Royal London Hospital, and now in private practice, says the risk of birth defects could be due to recent advances in IVF technology - notably, the development of a technique called intracytoplasmic sperm injection (ICSI). This was developed in 1992 to help infertile men become fathers, and is now used in about half of IVF treatments. The technique involves injecting a single sperm into an egg, rather than positioning many sperm close to the egg, as in standard IVF.

One study of 300,000 births, which caused shock waves when it was published in the New England Journal of Medicine last May, found that in almost 10% of births with ICSI, the baby had a birth defect, compared with less than 6 per cent in natural births. By contrast, it found that standard IVF had no significantly higher risk of birth defects than natural conception.

Dr Grudzinskas, however, says the type of abnormality found in babies born after ICSI is "mostly minor" and easily corrected by surgery. One common problem is hypospadias, an abnormality in the development of the penis, which, he says occurs in 1 in 100 naturally occurring births - and one in 60 after treatment with ICSI.

"Of course it is a shock that your child is not as perfect as you want it to be - but as with many mild abnormalities this can be corrected by surgery and the child will function and develop perfectly normally."

Researchers are uncertain whether the IVF process or some other factor is involved in the rise in defects.

Specialists say that one factor could be the increasing age of women having IVF - in the UK about one third of women using it are over 35 - although Dr Boyle points out that older mothers are more at risk of having babies with chromosomal abnormalities rather than the kind of physical defects seen in the study.

There is also the possibility of an underlying health issue that could cause birth defects among couples who opt for hi-tech treatment.

Dr Elson says: "The jury is still out on whether it is IVF, the age of the woman or a problem with the sperm or egg that contributes to the risk of birth defects in couples having fertility treatment."

In addition, Dr Grudzinskas argues that ICSI is being used too widely, because it is wrongly thought by many couples to have higher success rates than standard IVF. "ICSI only has higher success rates where the man has a problem, otherwise the success rates are the same" he says. "ICSI should only be used where there is low or no fertility in the man."

The HFEA's scientific committee is calling for more research into IVF- associated birth defects. In the meantime, Dr Grudzinskas advises that couples - and their doctors - should view ICSI with caution, while women who have twin pregnancies after IVF should be provided with specialist antenatal care and screening.

Couples embarking on IVF, he adds, should be counselled specifically about the potential risk of birth defects. "Staff working in this area often leave it to the patient leaflet on the subject."

Would a small potential risk of birth defects put many couples off? Karen Veness, spokesman for the charity Infertility Network UK, believes it would make no difference for most.

"I conceived my first daughter by IVF 15 years ago," she says. "I wasn't told about potential problems, though I'm sure things are different now. If I was doing it again, and knew more about the risks, I wouldn't feel differently. The desire to have your own child is so overwhelming - for most women it wouldn't be an issue."