Progesterone (P4) is essential for endometrium support, and on that account for successful embryo implantation and maintaining a healthy pregnancy.

During the In Vitro cycle, therapy that affects progesterone levels is usually used to prevent premature ovulation.

There is an ongoing debate regarding progesterone levels before embryo transfer.

According to some studies, supplementing with this hormone increases the success rates of the In Vitro cycle and results in a healthy fetus. However, there are differing opinions on whether support with P4 reduces the rates of miscarriage or biochemical pregnancy or whether it has no effect on the outcome.

Although progesterone levels on the day of transfer have not yet been extensively studied, the timing of the frozen embryo transfer based on serum P4 values, and not just based on the number of the days in the menstrual cycle, has shown to result in higher pregnancy rates, maximize implantation rates and reduce abortion rates.

There are currently four different ways to administer progesterone: vaginal, intramuscular, subcutaneous, and oral administration.

When comparing pregnancy supplementation with choriogonadotropin (HCG), the use of P4 is preferred to HCG because it works better In Vitro cycles and is less likely to cause ovarian hyperstimulation syndrome. Therefore, it is important to understand the impact of P4 support and optimal P4 values during the in vitro cycle.

The opinion is that P4 values should be maintained between 10 and 20 ng/ml during the luteal period before implantation in order to maximize the implantation rate. Values of P4 > 40 ng / ml, on the other hand, indicate a lower implantation rate and a higher abortion rate after In vitro fertilization.

However, controversy continues to exist in the literature regarding optimal P4 values, probably due to variations in patient characteristics, including uterine dynamics, progesterone absorption and utilization.