NEW YORK (Reuters Health) – Twins conceived by test tube or
“in vitro fertilization” (IVF) are more likely than twins
conceived through sexual intercourse to be born prematurely and
to be delivered by c-section, a review of previous studies
suggests.
IVF has led to an increase in the number of preterm births
and low birth weight infants, but the mothers of these infants
are typically older and at higher risk of both outcomes,
explain Dr. Sarah McDonald from University of Ottawa, Ontario,
Canada and colleagues in the American Journal of Obstetrics and
Gynecology.
They therefore compared the rate of adverse birth outcomes
for 2303 IVF twins and 2326 spontaneously conceived twins born
to women of similar age.
IVF twins were around 50 percent more likely than
spontaneously conceived twins to be born preterm, the
investigators report, but there were no differences in the
likelihood of having a low birth weight.
IVF twins were also twice as likely to be admitted to the
intensive care unit and 33 percent more likely to undergo
c-section than were spontaneously conceived twins, the report
indicates.
The two groups of twins did not differ in the rates of
stillbirth, very low birth weight, or major complications of
delivery, the researchers note, and there was no difference in
the rate of birth defects.
“IVF twins have worse perinatal outcomes than spontaneously
conceived twins who are matched for maternal age,” the team
concludes.
Possible reasons for the increase in preterm birth “include
a factor inherent to the IVF technology, a history of
infertility itself, or physician or patient anxiety,” the
investigators speculate.
SOURCE: American Journal of Obstetrics and Gynecology, July
2005.
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