Progesterone for recurrent miscarriage: truth and deceptions.

Recurrent miscarriage is known to affect 0.5-2% of pregnant women, and the standard investigative protocol fails to identify a specific cause in 50% of cases. Progesterone, a key hormone in pregnancy maintenance, has been used to support early pregnancy for decades. A growing body of considerable evidence indicates that in addition to women with luteal phase defects, women with idiopathic recurrent miscarriage may benefit from progestogen treatment, as progesterone has been shown to be an essential immunomodulatory agent in early pregnancy. It plays a critical role in the expression, modulation and inhibition of various growth factors, cytokines, cell adhesion molecules and decidual proteins. Some studies have revealed a remarkable improvement in pregnancy outcome after progestogen supplementation in women suffering from recurrent miscarriage. As most studies on this topic are of unsufficient statistical power, further research on the efficacy of progestogen treatment in affected women is required.