Background
The transfer of fresh embryos is generally preferred over the transfer of frozen embryos
for in vitro fertilization (IVF), but some evidence suggests that frozen-embryo transfer
may improve the live-birth rate and lower the rates of the ovarian hyper stimulation
syndrome and pregnancy complications in women with the polycystic ovary syndrome.
Methods
In a multicenter trial, we randomly assigned 1,508 infertile women with polycystic ovary
syndrome who were undergoing their first IVF cycle to undergo either fresh-embryo
transfer or embryo cryopreservation followed by frozen-embryo transfer. After three
days of embryo development, women underwent the transfer of up to two fresh or
frozen embryos. The primary outcome was a live birth after the first embryo transfer.
Results
Frozen-embryo transfer resulted in a higher frequency of live birth after the first transfer
than did fresh-embryo transfer (49.3% vs. 42.0%).
Women who underwent frozen-embryo transfer also had a lower frequency of
pregnancy loss (22.0% vs. 32.7%) and ovarian hyper stimulation syndrome (1.3% vs.
7.1%), but had a higher frequency of preeclampsia (4.4% vs. 1.4%).
There were no significant between-group differences in rates of other pregnancy and
neonatal complications. There were five neonatal deaths in the frozen-embryo group
and none in the fresh-embryo group.
Conclusion
Among infertile women with polycystic ovary syndrome, frozen-embryo transfer was
associated with a higher rate of live birth, a lower risk of the ovarian hyperstimulation
syndrome, and a higher risk of preeclampsia after the first transfer than was fresh-
embryo transfer.