Preterm births explain cerebral palsy risk after IVF

NEW YORK (Reuters Health) – Research confirms that the
reason more children born after in vitro fertilization (IVF)
have a higher than average risk of cerebral palsy is largely
due to the association between IVF and preterm delivery.

In a study that included all live, single infants and twins
born in Denmark within a 6-year period, preterm birth was “the
most powerful predictor of cerebral palsy,” report
investigators in the medical journal Pediatrics.

Preterm birth is “a major step on the causal path to
cerebral palsy among IVF children, for single infants as well
as twins,” Dr. Dorte Hvidtjorn from the University of Aarhus
and colleagues note.

“These findings, which are consistent with other studies,
are of great public health importance,” they add, “and call for
prevention of the high rate of multiple births and preterm
deliveries in IVF.”

Included in the team’s analyses were 9,255 children
conceived through IVF and 394,713 children conceived without
IVF. Infants born after IVF, a common method of assisted
reproduction, are sometimes referred to as “test tube” babies.
An egg and sperm are combined and resulting embryo is implanted
into the uterus. Usually several embryos are implanted into the
womb to increase the chances of a successful implantation.

In the first analysis of the study, IVF children compared
with non-IVF children had a 61-percent increased risk of
cerebral palsy. However, the independent effect of IVF
disappeared after information on multiple and preterm births
was factored into the analysis, according Hvidtjorn and
colleagues.

This indicates that the increased risk of cerebral palsy
for IVF children is “largely attributable to the large
proportion of IVF children who are born preterm (especially
because a large proportion of IVF children are both born as
multiple births and born preterm) and not to the treatment
itself.”

SOURCE: Pediatrics, August 2006.