Use of progestogens in pregnant and infertile patients.

Progesterone is an essential hormone in the occurence and maintenance of pregnancy. Natural or synthetic progestogens are commonly used in pregnant patients or patients undergoing infertility treatments for various indications. Most frequently put indications for the use of progestogens in these patient populations are the prevention of spontaneous preterm birth, the prevention of pregnancy loss in pregnancies with an unexplained recurrent pregnancy loss and in patients with threatened abortion. It is also used in pregnant women undergoing nonobstetric surgery, for infertility or recurrent pregnancy loss that is thought to be due to luteal phase defect or as a luteal support in stimulated IVF cycles. We aimed to review the current evidence for the use of progestogens in each of these settings.