The jury is still out on the increased risk of cerebral palsy in children born as a result of fertility treatment, researchers say today.
Children born after in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) tend to have higher rates of cerebral palsy, but experts are unsure whether this is due to the treatment, the risk of premature or multiple births, or the couples’ infertility.
Dr Jin Liang Zhu and colleagues at the University of Aarhus in Denmark, used figures from the Danish National Birth Cohort to compare children born after different durations of attempting to conceive, as a marker for fertility problems.
They took into account a range of health factors, and found no link between time to pregnancy and risk of cerebral palsy. Full results appear in the journal Human Reproduction.
"Our research enabled us to examine whether untreated subfertility, measured by time to pregnancy, might be the reason for the higher risk of cerebral palsy after IVF/ICSI," explained Dr Zhu.
"Our results showed that this was not the case because, even for couples who took a year or longer to conceive, there was no statistically significant increased risk if they conceived spontaneously."
However, children born after IVF/ICSI had more than twice the risk of cerebral palsy. But Dr Zhu points out that the risk of cerebral palsy is still low, at about one in 176 babies. "More research is needed," he concludes.
A second, larger study in Sweden recently found no significant link between cerebral palsy and IVF/ICSI.
Professor Karl Nygren of the European Society of Human Reproduction and Embryology said: "The previously noted increased risk of cerebral palsy after IVF is certainly decreasing and may actually have disappeared in recent years in countries that only transfer a single embryo at one time."
Zhu, J. L. et al. Parental infertility and cerebral palsy in children. Human Reproduction, published online November 3, 2010.
Kallen, A. J. et al. Cerebral palsy in children born after in vitro fertilization. Is the risk decreasing? European Journal of Paediatric Neurology, Vol. 14, November 2010, pp. 526-30.
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