[Introduction]
Abdominal trachelectomy (AT) has been used as a fertility-sparing surgery for early-stage cervical cancer in women of reproductive age since the first report (Smith JR, 1997) on the same was published,1 and is defined as surgical removal of the uterine cervix with preservation of the uterine body. The incidence of cervical cancer in reproductive-aged women is increasing,2-4 and the number of women desiring pregnancy after AT is also increasing accordingly. Many reports on obstetric outcomes in pregnant women after AT in the past have described the high risk of miscarriage, preterm birth, and preterm premature rupture of membranes (pPROM).5-9 The reported incidence of preterm birth and miscarriage ranges from 53% to 89%,6-10 and the high rate of complications in pregnant women after AT can be attributed to the loss of the supporting tissue of the cervical canal that maintains pregnancy and ascending infection due to the loss of the cervical mucus plug. Although the high risk of miscarriage has recently been well recognized, a preventive approach for pregnancies after AT has not been discussed.
The efficacy of progesterone administration in preventing preterm birth in high-risk pregnant women such as those with a history of preterm birth11,12 or women with a shortened cervix13,14 has recently been established, and the use of this drug for managing such high-risk pregnancies has become common in Western countries.15,16 The mechanism of action of progesterone responsible for preventing preterm birth has not been fully determined, but the preventive effect is speculated to be caused by its anti-inflammatory effect, decreased cervical stromal degradation, and a decreased frequency of contractions of the myometrium.17 The efficacy of progesterone in preventing preterm birth in high-risk pregnancies is unquestioned; however, to the best of our knowledge, the use of progesterone for reducing the risk of preterm birth in pregnant women after AT has not been reported to date.
Against this background, we designed an interventional study to determine whether vaginal progesterone (VP) reduces the rate of preterm birth in pregnant women after AT.