Was the preterm birth rate in the placebo group too high in the Meis MFMU Network trial of 17-OHPC?

Abstract

The rate of recurrent preterm birth for women in the placebo arm of the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units (MFMU) Network randomized trial of 17 alpha-hydroxyprogesterone caproate (17-OHPC) was 54.9%.1 This rate has been called “strikingly high,”2 thus “calling into question the apparent risk reductions associated with progesterone therapy.”3 Because the recurrence rate in the treatment arm (36.9%) was similar to recurrence rates in another MFMU Network observational study,4 the high rate of recurrence has been suggested3,5 to be the result of uterotonic effects of castor oil, the vehicle used in both arms of the Meis trial.