In September 2019 in the “Fertility and Sterility” journal, a meta-analysis study on the effect of progesterone on increased rate of pregnancy in fresh IVF cycles. The authors compared progesterone application methods, the beginning of therapy, length, and combination with estrogen. The study included publications from 1983 to 2018, with 26 726 women in IVF procedures.

It is already known that taking progesterone as the support for corpus luteum in IVF cycles significantly increases pregnancy rates. A higher positive impact on clinical pregnancy rates was found from the intramuscular application of progesterone (OR 1.37), than from vaginal application. The optimal time for the beginning of progesterone therapy was the period between oocyte retrieval and embryo transfer; ideally in one day from oocyte retrieval. The study showed that simultaneous administration of estrogen does not increase pregnancy rates. Furthermore, prolonged progesterone administration also does not affect pregnancy rates since there were no differences in pregnancy rates when progesterone was administrated 3 weeks after oocyte retrieval or was continued until the 12^th week.

In BetaPlus, we recommend that progesterone administration starts the same day as oocyte retrieval, in the evening. Because of its simplicity, we usually recommend vaginal application. We also use intramuscular progesterone supplementation which we recommend for patients over 40 with embryos that are prospective, or in patients that previously had unsuccessful IVF procedures. Currently, progesterone administration is recommended until 8 weeks of pregnancy (6 weeks post oocyte retrieval).