Study population and design
This was a prospective interventional study that commenced in October 2016. The Kyushu University Hospital Ethical Review Board approved the study, and all work was conducted in accordance with the Declaration of Helsinki (1964). The enrollment criterion was women with singleton pregnancies after the second trimester who had previously undergone AT for early-stage uterine cervical cancer at our hospital. The exclusion criteria were abortion during early pregnancy, contraindications for progesterone use, multiple pregnancies, women who had undergone AT in other hospitals, and fetuses with severe anomalies or abnormal chromosomes. Eligible women were invited to participate in this study and sign a consent form. After obtaining informed consent, we started vaginal progesterone administration.
The primary outcomes of our study were gestational age at delivery and the incidence of preterm birth before 37 weeks and 34 weeks of gestation. The secondary outcomes were the incidence of pPROM and other obstetric complications, maternal adverse events (transfusion for massive vaginal bleeding, hysterectomy after cesarean section, septic shock, and maternal death), and neonatal morbidity and perinatal mortality (fetal death and neonatal death). We investigated these outcomes among the study participants and compared them with those of the historical control group participants. The historical control group included women with singleton pregnancies after AT who were managed without VP at our institution between January 2007 and September 2016. Data of the historical control group participants were collected retrospectively by reviewing both maternal and neonatal medical records of each participant. In 2017, we reported the perinatal outcomes of singleton pregnancies after AT18 managed between March 2005 and October 2015, and the historical control group in this study partly overlapped with that reported in the previous study.