Freezing embryos prior to in vitro fertilization may lead to more successful ongoing pregnancy rates in women who undergo in vitro fertilization using their own eggs.
That’s the result of a recent study by several private and academic fertility centers around the United States.
The study, which took a look at 1,455 IVF transfers, revealed that embryos transferred after being frozen were more likely to result in an ongoing pregnancy than embryos transferred within days of being created. Fifty-two percent of embryos that had been frozen and implanted later resulted in ongoing pregnancies, while 47 percent of embryos implanted soon after they were created resulted in pregnancy.
The ongoing pregnancy rates were most significantly improved for women who showed high progesterone levels following egg retrieval. Higher progesterone levels may make it harder for embryos to successfully implant and grow. Researchers speculate that freezing embryos and waiting until uterine conditions are more favorable leads to stronger outcomes.
“This finding is important because it may suggest a group of women that benefits more from freeze-all IVF cycles,” says Dr. Ange Wang, a resident physician in obstetrics and gynecology at Stanford University. In freeze-all cycles, all embryos are frozen for later transfer. “Higher progesterone levels may make it more difficult for embryos to implant — that is, adhere to the wall of the uterus to establish pregnancy — possibly due to premature maturation of the uterine lining.”
The most significant improvement was seen in women over the age of 35 with elevated progesterone levels.
What does that mean for you? If you are a woman over 35 and considering in vitro fertilization using your own eggs, you may want to discuss freezing your embryos and waiting to implant them when progesterone levels are lower.
But that might not be the right choice for you, and you should discuss it with your partner and your care team. Waiting to implant embryos may place additional emotional or financial strain on you, and it’s important to take all of those factors into consideration before making your decision.