Objective To determine whether vaginal progesterone (VP) reduces the rate of preterm birth in pregnant women after abdominal trachelectomy (AT) for early-stage cervical cancer Design Prospective cohort study with a historical cohort Setting University hospital Population Twelve pregnancies in ten women were included in the VP group between October 2016 and September 2020. By contrast, 19 pregnancies in 17 women were included in the historical control group between January 2007 and September 2016. Methods For the interventional study participants, the administration of vaginal progesterone was started between 16+0 and 19+6 weeks of gestation and discontinued at 34 weeks of gestation or at the time of delivery, rupture of membranes, or massive uterine bleeding, whichever occurred first. We investigated obstetric and neonatal outcomes among the study participants and compared them with outcomes of the historical control group participants. Main Outcome Measures The gestational age at delivery and incidence of preterm birth before 37 weeks and 34 weeks of gestation Results 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 incidence of preterm birth in the two groups was similar, and the difference between the two groups was not statistically significant. Conclusions The administration of vaginal progesterone did not reduce the rate of preterm birth among pregnant women after AT.