Women trying to get pregnant through in vitro fertilization (IVF) may have more success if they’re implanted with previously frozen embryos rather than fresh ones, a new study suggests.
Researchers in China randomly assigned more than 1,500 women to IVF treatment using either fresh embryos, or embryos that were first frozen and then thawed before being implanted in the women’s uterus. All the women were between 20 and 34 years old and had a condition called polycystic ovarian syndrome, or PCOS, which can cause pregnancy problems.
Although the women got pregnant at roughly the same rate, the women implanted with previously frozen embryos were more likely to stay pregnant and give birth. Close to half – 49 percent – of the women in the frozen embryo group ended up giving birth, compared to just 42 percent of women in the fresh embryo group.
The researchers noted other benefits among the women implanted with frozen embryos: They were less likely than their fresh-embryo counterparts to experience ovarian hyperstimulation syndrome (when ovaries become swollen and painful), and their babies tended to weigh more at birth.
On the downside, the women implanted with previously frozen embryos also suffered a higher incidence of preeclampsia, a serious pregnancy complication characterized by high blood pressure.
So should you insist on frozen embryos if you’re having IVF treatment? Results from a randomized trial of this size are certainly significant. However, this study only involved women with PCOS, so women undergoing IVF who don’t have this condition might not experience the same results.
Another note of caution: among the frozen embryo group there were 2 stillbirths and 5 neonatal deaths. The fresh embryo group had neither. That could be just a coincidence since the numbers are too small to show a trend, but the authors said it “warrants attention.”
Have you had, or would you consider, in vitro fertilization using frozen embryos? Why, or why not?
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