Progesterone helps support implantation and the IVF process blunts your body’s natural ability to make progesterone. When one undergoes a fresh IVF cycle for example, all of those follicles that are aspirated at the time of egg retrieval makde progesterone but the hormone signals from the brain that KEEP those follicles making progesterone is blunted by the IVF medications that are responsible for prevented ovulation. As a result, progesterone supplementation is required in IVF.
Which route and for how long, though, have been questions studied for some time and practice patterns vary by clinic so talk to your MD about what is right for you.
Studies have shown that progesterone injections are equivalent to vaginal progesterone suppositories in FRESH IVF cycles as it relates to livebirth rates. Interestingly, some patients prefer injections over vaginal suppositories. Eitherway, if you are not tolerating injections, talk to your doctor about whether vaginal progesterone is right for you.
Progesterone and FET: Differences
Unlike in a fresh IVF cycle where your body makes some progesterone, in *most* frozen embryo transfer (FET) cycles, your body does not make any progesterone. As a result, FET cycles are completely reliant on progesterone as a REPLACEMENT.* There are fewer studies and less agreement about the equivalence of progesterone injections and progesterone vaginal suppositories in FET cycles. So. More clinics might prefer progesterone injections in FET cycles.
*SIDENOTE: some clinics have moved to modified natural cycle FET preps in which the luteal phase is supported by the body’s own progesterone AND supplemented with exogenous progesterone as well.
How long do I need to take this?
Progesterone production is the domain of the ovary until the placenta takes over progesterone production at around 8-10 weeks gestational age. Because of the estimated timing and the desire to be conservative, most IVF clinics in the US recommend progesterone supplementation for 8-10 weeks after egg retrieval/FET. Again talk to your MD if you have questions about your specific situation.
Do I need to check progesterone levels while on progesterone?
There is a lot of variation on this among clinics. Some do it, some don’t. Clinics that check it might adjust progesterone doses based on the level.