Recurrent or threatened miscarriage

Inadequate production of progesterone in the early part of pregnancy may be a causative factor in some cases of miscarriage. Progesterone supplementation, starting in the first trimester, is frequently prescribed to prevent spontaneous miscarriage and recurrent miscarriage of unknown etiology.24
A few studies have evaluated the use of oral NMP in the setting of threatened spontaneous miscarriage in the first trimester (Table 2 ). A retrospective cohort study found that 88% of women with a threatened spontaneous miscarriage treated with oral NMP 200 mg twice daily were discharged home with a healthy pregnancy.25A RCT (n = 60) that evaluated first-trimester placental and foetal volumes showed that oral NMP 400 mg/day had beneficial effects in terms of significantly increasing placental volume compared to no treatment, although no significant difference was seen in the live birth rate or perinatal complications (assessed as secondary endpoints).26 Finally, a recent comparative RCT (n = 118) found that oral NMP 200 mg twice daily was as effective as dydrogesterone 10 mg twice daily at reducing bleeding and rate of miscarriage.27