Understanding When Embryo Transfer Occurs
For many women and couples, in vitro fertilization (IVF) is one of the few options available to conceive successfully. But IVF has a very specific timeline, especially for frozen embryo transfers (FET), which can leave some people confused as to when specific processes take place. For example, when does embryo transfer begin, and when does the event occur after a woman gets a period?
The IVF process explained
IVF is a treatment that helps women and couples conceive when natural methods haven’t worked in the past. Usually, eggs are retrieved from a woman’s ovaries and fertilized with sperm either from a partner or donor outside of the woman’s body. After mixing the eggs and sperm, if fertilization occurs, the embryos are then transferred to a woman’s uterus for implantation. Ideally, a healthy pregnancy begins. However, in FET, some of the preparatory steps are skipped since a woman won’t need to undergo ovarian stimulation or egg retrieval.
Why choose FET IVF
FET IVF is a popular choice for women who had multiple eggs retrieved in a previous IVF cycle. Typically, fertility specialists will only transfer one or two embryos into a woman’s uterus within one cycle. But if multiple viable embryos were formed in a previous cycle, a physician may recommend freezing the remaining embryos to use at a later date. And in other cases, if a couple or woman is using a donor embryo, then a frozen embryo is the most likely source.
Hormonal support versus natural FET IVF cycles
As noted earlier, ovarian stimulation and egg retrieval aren’t part of a FET IVF cycle. The two most common types of FET IVF can include natural and hormonal monitoring. In natural monitoring, a woman is not placed on hormones but instead, ovulation is closely tracked to accurately time the optimal time to start an embryo transfer. In hormonal monitoring, a woman will be given hormonal injections at the end of the last menstrual cycle and undergo testing. Additionally, estrogen supplementation may be included, which will last for two weeks, followed by progesterone.
FET IVF transfers explained
Timing for FET depends on whether a woman is undergoing a natural or hormone-supported FET IVF cycle. In a hormone-supported cycle, embryo transfer tends to occur after progesterone supplementation begins, and the exact date depends on when the embryo was frozen. Usually, this happens anywhere between day 3 or 5 post-egg retrieval, with the transfer taking place on the subsequent day 6 from when progesterone supplementation began. For natural FET IVF cycles, the transfer takes place depending on a woman’s natural ovulation cycle, which is why monitoring is crucial. Usually, specialists will rely on bloodwork to accurately pinpoint ovulation and schedule the transfer accordingly.
So when does transfer occur?
In short, embryo transfer can occur within a regular ovulation window after a recent period for women undergoing natural FET IVF cycles or within 3-4weeks after the recent period for women with hormonal support FET IVF. The process can be an emotionally trying time for women and couples who are trying to conceive. But women undergoing the procedure should continue to take any prescribed fertility medications, especially immediately after embryo transfer is completed to ensure successful implantation and subsequent pregnancy. Additionally, try to resist the urge to immediately take a pregnancy test as getting a big fat positive result can take as long as two weeks from the embryo transfer date. For more information, speak with a fertility specialist.