Retrospective Analysis of Mifepristone for the Cervical Preparation of Labour Induction in Live Births

Background: Mifepristone is a synthetic antagonist of progesterone and glucocorticoid receptors that is sometimes used for the induction of labour. However, because it is licensed as an abortive agent, its safety profile in healthy deliveries may be of concern. Therefore, this study aimed to evaluate the maternal and neonatal safety of mifepristone for the preparation of labour induction. Methods: This was a retrospective cohort study of 105 women with singleton pregnancies who received 600mg mifepristone for preparation for induction of labour between 24 and 42 weeks of gestation in the Department of Gynaecology and Obstetrics of the Klinic Donaustadt, Austria, from April 2017 until March 2022. Maternal, pregnancy, induction, delivery, and foetal characteristics were collected and compared between very preterm (24-31 weeks of gestation, n=10), moderate/late preterm (32-36 weeks of gestation, n = 45), and term (37-42 weeks of gestation, n = 50) groups. Results: The women were aged 31.3±5.6 years, the mean gestational age at delivery was 35.9±3.3 weeks, and all deliveries resulted in a live birth. Fifty-three (50%) of women in the cohort required no other agent for the inductiosn of labour. Spontaneous delivery was possible for 48 (46%) women, 12 (11%) required vacuum delivery, and 45 (43%) Caesarean section. The very preterm group had 100% admission to NICU, the moderate/late preterm group had 43% admission, and the term group had 16% admission (P<0.001). Two women were admitted to the ICU in the term group. Hospital stay in the very preterm group was 57 (32-160) days compared to 10 (1-49) days in the moderate/late preterm group and 4 (2-60) days in the term group (P<0.001). There were no cases of uterine hyperstimulation, abnormal foetal heart rate patterns, neonatal hypoglycaemia, or polysytole. There were two cases of neonatal death after live birth, one in the early preterm group and one in the moderate/late preterm group. Conclusions: This analysis of women and newborn infants who received 600mg mifepristone for induction of labour identified no safety concerns for mother or newborn infant and could be a new strategy to reduce the number of caesarean sections.