Does first trimester progesterone prophylaxis increase the live birth rate in women with unexplained recurrent miscarriages?

Miscarriage is the commonest complication of pregnancy, occuring in one in six clinically recognised pregnancies.1 Recurrent miscarriage is the loss of three or more consecutive pregnancies. Women with recurrent miscarriage (in contrast to women with sporadic miscarriage) tend to lose genetically normal pregnancies.1 After comprehensive investigation, a cause for recurrent miscarriage is identified in less than half of couples.1 Most couples are therefore labelled as having unexplained recurrent miscarriage. Progesterone, secreted by the corpus luteum and the placenta, has a central role in maintaining a pregnancy.1 It is theoretically plausible that progesterone supplementation may reduce the risk of miscarriage in women with a history of recurrent miscarriages, and the first trial using progesterone for such women was published in the BMJ in 1953.2 This …