Does Progesterone Prevent Preterm Labor in Complicated Monochorionic Twin Pregnancies after Radiofrequency Ablation of One Fetus?

 Twin pregnancies have a higher risk of preterm labor than singletons. Otherwise, progesterone using to reduce the risk of preterm labor in twin pregnancies remains controversial. Therefore, this study evaluated the effect of intramuscular progesterone to prevent preterm labor in complicated monochorionic diamniotic twin pregnancies after Radiofrequency Ablation (RFA) of one fetus.

 Pregnant women with monochorionic diamniotic twin pregnancies of 16 to 26 weeks of gestational age in an academic center were randomly assigned to receive intramuscular 17-hydroxy progesterone caproate weekly until 36 weeks of gestational age after RFA of one fetus and a control group who did not receive intervention after RFA. Demographic and obstetrical characteristics, as well as maternal, fetal and neonatal outcomes were compared between groups. 

 In total, 79 participants were recruited in the study. The mean±SD of gestational age at delivery in case and control groups were 34.6±3.8 and 34.6±5.1 with no significant difference (p=0.967). Neonatal outcomes including birth weight (p=0.870), intensive care unit admission (p=0.415), premature preterm rupture of membrane (p=0.115) and pregnancy outcome (live birth, fetal demise or neonatal death) (p=0.524) were not different either. Indeed, gestational age at delivery was inversely related to cervical length at the time of procedure and maternal body mass index, but these differences were not statistically significant. Also, there was no significant difference in terms of gestational diabetes, which was a worrying complication of 17-hydroxy progesterone caproate. 

 Although 17-hydroxy progesterone caproate seems to be safe with no apparent maternal and neonatal side effects, it does not prolong pregnancy after RFA. Further studies with longer follow up and larger sample size are suggested.