Study links IVF to birth problems

Dr. Kirsty Horsey

Progress Educational Trust

24 January 2004

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[BioNews, London] Babies born following fertility treatment are more likely to be premature and to have a lower birth weight than those conceived naturally, according to a group of Dutch and Australian researchers. Their findings, published in the British Medical Journal, indicate that single IVF babies are more likely to face birth problems than naturally conceived singletons, but that the risks faced by twins are higher than for either group. The authors of the new study, carried out at the University Medical Center, Leiden, in the Netherlands and Flinders University in Adelaide, Australia, say that women undergoing assisted reproduction should be informed of the increased risks in singleton pregnancies.

Previous studies have indicated that IVF is associated with an increased risk of low birthweight and premature birth, but this is partly because IVF is more likely to result in a multiple pregnancy. Twins and triplets, whether conceived naturally or using assisted reproduction techniques, are known to face a higher rate of birth problems than single babies. To carry out the latest research, the authors combined the results of 25 previous studies on the health of IVF babies, and looked at the outcomes of singleton and twin pregnancies separately.

Their findings suggest that compared to naturally conceived singletons, single IVF babies are twice as likely to be born before 37 weeks gestation, and three times more likely to be born before 32 weeks. The researchers also found that single IVF babies were three times more likely to have a very low birthweight, and were slightly more likely to encounter other birth complications. However, Australian IVF expert Gab Kovacs stressed that the risk of an IVF baby being born before 32 weeks was still small: 'Although the risk is three times more, we are talking only one or two in 100 births. It is still uncommon' he said. He also speculated that the early arrival and lower weights of IVF babies could be related to the original fertility problems. Another study of 56,000 births, reported in November 2003, found that couples who took longer than a year to conceive were more likely to have premature and low birthweight babies. This was true of women who eventually conceived naturally, as well as those who underwent fertility treatment.

For twin pregnancies, the researchers found that the risks are slightly lower following IVF than for twins conceived naturally. However, the authors say that because of the much greater risks of twin pregnancies overall, 'it may be timely to consider any multiple pregnancy after assisted conception as a failure of that technology to achieve what it ought to achieve'. UK expert Alastair Sutcliffe, of University College London agreed that it was important not to downplay the risks faced by twin babies compared with single babies: 'The biggest risks faced by an assisted reproduction baby are those produced by a multiple birth' he said.

Reproduced with permission from BioNews, an email and online sources of news, information and comment on assisted reproduction and genetics.