Q: I am supposed to start using Progesterone in oil injections during my upcoming IVF cycle. I believe this is a ‘NATURAL’ form of progesterone, but wanted to be sure. I have read that there may be a slight increase in birth defects associated with the ‘SYNTHETIC’ forms of progesterone (Progestins). I became a bit concerned upon reading the insert that accompanied the drug since it warns of potential risks associated with taking progesterone during the first trimester of pregnancy, including birth defects (genital deformities). I am assuming the FDA requires that the warnings be put in regardless of the type of progesterone, natural or synthetic, but would like some reassurance. Can you please help me to understand why we need to continue the use of the progesterone after implantation of a pregnancy? Are there other options such as Crinone (progesterone vaginal gel) which is approved by the FDA for use in assisted reproductive technology?
A: Most IVF programs use Progesterone in oil (intramuscular injection); Endometrin (vaginal tablets); Crinone or Prochieve (progesterone vaginal gel) and/ or Prometrium (oral progesterone). These are all natural progesterone preparations. There must be progesterone hormone support given in order to adequately develop and maintain the lining of the uterus (endometrium). After egg retrieval, most women can’t make enough progesterone hormone because many of the progesterone producing cells in the ovarian follicles are removed when the eggs are retrieved.
Progesterone is a natural hormone produced in women by the ovary after ovulation. Progesterone acts directly on the endometrial lining of the uterus to prepare it for accepting a pregnancy. Progesterone is also made by the placenta during pregnancy.
Although there is still controversy, the synthetic Progestins have been previously blamed for a slightly increased incidence of certain birth defects. More recent studies have indicated that the risk of congenital anomalies in women who inadvertently take synthetic Progestins during pregnancy are either not increased at all or are only slightly worse. Although these studies are reassuring, the FDA does not support the use of synthetic Progestins (Provera or birth control pills) during pregnancy. Most of us who specialize in infertility and hormonal therapy will use only natural progesterone for patients actively trying to conceive. The most commonly used natural progesterone preparations include:
Currently, no studies have demonstrated convincingly that the use of natural progesterone increases the risks to a baby. The FDA unfortunately lumps all natural progesterone and Progestins (synthetic) together, even though not a single study in over 50 years of use has convincingly demonstrated any problem. At times, natural progesterone has gotten a bad rap by being lumped into the same category as synthetic Progestins. You do not need to worry about using natural progesterone.