You may have had discussions with your physician or nurse regards to your progesterone level on the day of hCG (trigger injection). It may have been suggested that since the progesterone level is greater than 1.5 ng/mL, we should postpone embryo transfer and freeze all the embryos. Why do we suggest freezing of embryos due to this level?
Here is some background information that may be useful.
For an IVF cycle to work, a good quality embryo needs to be correctly placed in a receptive uterine lining (endometrium). Uterine receptivity is influenced by hormonal changes during the cycle. Initially, there needs to be enough estrogen on board to promote growth (proliferative phase) of the uterine lining. After ovulation, the hormone progesterone is released and induces “secretory” changes in the uterine lining, which make it receptive for the embryo. The duration of exposure to progesterone is a critical factor. If there is a longer exposure to progesterone the changes in uterine lining are advanced and make it less receptive for the embryo. In IVF, the hCG injection is required for the final maturation step for the eggs. It also induces changes that can lead to ovulation and release of progesterone. It is therefore normal for the progesterone level to rise the day after the hCG injection. It, however, is NOT good for the progesterone level to have risen prior to the hCG injection.
At present we do not have a clear answer as to what causes the progesterone level to rise prematurely in some patients. We therefore do not have a clear strategy for preventing this rise.
A recent publication from a busy IVF Center in Spain reported that a progesterone rise on day of hCG was associated with lower pregnancy rates. This happens in about 5% of cycles and occurs despite the use of medications to prevent premature ovulation (Lupron, Ganirelix etc). This was in contrast to previous reports that suggested that such a rise was not clinically important unless the progesterone level was really high (>2.5 ng/mL).
Based on this report, we started measuring progesterone levels on day of hCG. When we analyzed our data, we did confirm a drop in success rates when the progesterone level was greater than 1.5 ng/mL. We are continuing to monitor this level closely and it is possible that we may settle on a lower cut off.
At InVia, our fresh and frozen embryo transfer success rates are similar. It is indeed disappointing when your embryo transfer is postponed. However, most patients will agree that it is better to get pregnant a month later rather than having a negative outcome.