The randomised controlled trial of micronised progesterone and dydrogesterone (TRoMaD) for threatened miscarriage

There has not been conclusive evidence in literature on the efficacy of progestogen in the treatment of threatened miscarriage, although some studies showed benefits. In our centre, threatened miscarriage is treated with either micronised progesterone (MP) or dydrogesterone (DYD).

The aim of this study is to compare clinical outcomes of miscarriage, extent of vaginal bleeding at follow-up and side effects between treatment groups.

This study was a prospective parallel-group, open-label, randomized controlled trial. 141 women presenting with threatened miscarriage were randomised to either MP or DYD of which 118 were included in the analysis. Baseline maternal demographics and serum progesterone levels were collected at presentation. Post-treatment bleeding pattern and self-reported side effects were recorded at the follow-up visit (on day 4-10 of treatment). The occurrence of spontaneous miscarriage was ascertained at week 16 of gestation.

The population with miscarriage and resolution of bleeding were not statistically different between MP and DYD groups. A significantly higher percentage of women treated with MP reported drowsiness (p = 0.003). After stratification into low and high serum progesterone levels, a significantly higher miscarriage rate was found in the low progesterone group, regardless of treatment type.

In conclusion, extent of bleeding at day 4-10 and subsequent miscarriage rates were comparable between MP and DYD groups. However, fewer patients treated with DYD reported drowsiness and giddiness. The finding of significantly higher miscarriage rates in women with low progesterone levels despite treatment is an important factor to consider in counselling and prognosticating pregnancy outcomes.