IVF babies 'face birth problems'

Single IVF babies were twice as likely to be born early

Single IVF babies are more likely to be born early and weigh less than those conceived naturally, say experts.

The risk of a premature birth is roughly doubled, according to Dutch researchers, and there may be a slight rise in the risk of death after birth.

However, the overall risks to single babies are vastly outweighed by those faced by twins - both natural and IVF.

Writing in the British Medical Journal, the experts said doctors should do more to prevent problems at birth.

The study does not prove that the IVF itself is causing the difference.

It could be that the underlying health of women who end up needing IVF also has an impact on their ability to carry a baby to full term.

It has been understood for some time that babies born through fertility treatment are more likely to suffer problems.

This is partly due to the fact that IVF births are more likely to involve multiple babies, which automatically have a greater risk of prematurity and low birth weight.

Trouble confirmed

However, the Netherlands research, from Flinders University and Leiden University Medical Centre, combines the results of dozens of separate studies, and comes to the firm conclusion that even single pregnancies carry a higher risk.

The rate of preterm birth in singleton pregnancies after assisted reproduction is twice that seen with natural conceptions Researchers

There was limited evidence of a three times increased risk of having a very premature baby born prior to 32 weeks gestation.

In addition, there was just over a doubling of the risk of a "mildly" premature baby, born between 32 and 36 weeks.

IVF twins fared similarly to their naturally-conceived counterparts, although the overall risk faced by twins and other multiples is significantly higher than for single babies.

There was also a higher risk that IVF babies would be "small for dates" - that is, not weighing as much as would normally be expected for a baby born after a similar-length pregnancy.

Undermined

The authors of the study admit that weaknesses in the make-up of the studies they examined did undermine the results, but they said that the evidence remained compelling.

"Despite these limitations, it is clear that the rate of preterm birth in singleton pregnancies after assisted reproduction is twice that seen with natural conceptions.

"Singletons from assisted conception are significantly disadvantaged.

"Emphasis needs to shift, more than it has already, from achieving pregnancy to achieving a successful outcome."

Underlying disease

Explanations for the difference are not readily available.

One suggestion is that the fertility problems which led the women to seek treatment may interfere with the successful outcome of the pregnancy in some cases.

It could also be that underlying disease which makes it hard for a woman to conceive may have a wider effect on the developing foetus.

The biggest risks faced by an assisted reproduction baby are those produced by a multiple birth Dr Alastair Sutcliffe University College London

It is possible, say the researchers, that women having IVF may come from slightly different backgrounds and have subtly different lifestyles compared with those conceiving naturally.

Dr Alastair Sutcliffe, an expert from University College London, said it was important not to downplay the risks faced by twin babies compared with single babies.

And he said that unless the baby was premature by more than a few weeks, the actual outcome was likely to bear comparison with a full term baby.

He said: "Outcomes from 34 weeks or above are the same as for a term baby, more or less.

"The biggest risks faced by an assisted reproduction baby are those produced by a multiple birth."