[Results]
During the study period, 12 pregnancies in ten women were included in the VP group. In contrast, 19 pregnancies in 17 women were included in the historical control group. Results from the comparison of the oncological background characteristics of the ten women in the VP group and 17 women in the historical control group, and the baseline maternal characteristics of the 12 pregnancies in the VP group and 19 pregnancies in the historical control group are shown in Table 1. The cancer stage and operative procedures were similar in the two groups. Age at delivery and the rate of assisted reproductive technology use were similar between the two groups; one egg donation-embryo transfer was noted in the VP group. The median duration between surgery and delivery was somewhat longer in the VP group than in the control group, but the difference was not statistically significant.
Table 2 shows the pregnancy and perinatal outcomes. The incidence of preterm birth at <37 weeks was 10/12 (83%) in the VP group and 11/19 (58%) in the control group, and the incidence of preterm birth at <34 weeks was 6/12 (50%) in the VP group and 9/19 (47%) in the control group. The difference in the incidence of preterm birth between the two groups was similar and not statistically significant. The most common cause of preterm emergency cesarean section was pPROM in both groups. Figure 1 shows the distribution of gestational age at delivery in both groups. The median gestational age at delivery was 33+6 weeks (range: 26+0 to 37+4 weeks) in the VP group and 34+6weeks (range: 23+5 to 37+5 weeks) in the control group. No miscarriages (delivery <22 weeks) occurred in either group. The incidence of pPROM was 6/12 (50%) in the VP group and 8/19 (42%) in the control group. The median gestational age at pPROM tended to be earlier in the VP group than in the control group, although the difference was not statistically significant. In the VP group, intrauterine fetal death occurred at 32 weeks of gestation in one case. The fetal anatomic survey was unremarkable, and the cause of fetal death was undetermined. Other pregnancy and perinatal outcomes were similar between the two groups.
Table 3 shows the maternal adverse events. Of the total number of pregnant women, abnormal massive vaginal bleeding from vaginal or cervical varices during pregnancy occurred in eight women, and three women from the VP group and four from the control group required blood transfusion. In the control group, total abdominal hysterectomy (TAH) after cesarean section was performed in two women. The indications for TAH were placenta accreta in one and septic shock due to the development of an intra-abdominal abscess following cesarean section in another. In the VP group, no side effects of progesterone were noted.
Table S1 shows the neonatal outcomes of the 30 liveborn infants. In the control group, an infant death occurred in one case. The birth weight, number of admissions to the Neonatal Intensive Care Unit, and other neonatal outcomes were similar in the two groups. Of the study participants, 17 infants have already reached 1.5 years of corrected age. Regarding neurodevelopmental outcomes, in the control group, cerebral palsy was noted in one of the infants. None of the infants had mental retardation or epilepsy.