▲Professor Jin-Hoon Chung of the Department of Obstetrics and Gynecology at Asan Medical Center is consulting a patient with a twin pregnancy.

Cervical cerclage, a procedure that involves tying the cervix in a circle with stitches to prevent preterm birth, is commonly performed on a woman carrying a single fetus who have a history of preterm delivery and a cervical length of less than 2.5 centimeters before 24 weeks of pregnancy. However, there are no clear guidelines for twin pregnancies, leading to unnecessary cervical cerclage in some cases simply because the patient is carrying twins. A team led by Professor Jin-Hoon Chung of the Department of Obstetrics and Gynecology at Asan Medical Center recently published study findings that suggest cervical cerclage may, in fact, increase the risk of preterm birth in twin pregnancies where the cervical length exceeds 2.5 cm.

Out of 2,638 mothers who gave birth to twins at 10 tertiary hospitals in South Korea between January 2019 and June 2021, the research team targeted 1,339 mothers who had cervical length exceeding 2.5 cm before 24 weeks of pregnancy to analyze whether they underwent cervical cerclage and the occurrence of actual preterm births. The average gestational age (pregnancy period) was 35.9 weeks for mothers whose cervical length exceeded 2.5 cm before 24 weeks of pregnancy and who did not undergo cervical cerclage (N=1,320). In comparison, the average gestational age was 33.8 weeks in those who underwent cervical cerclage (N=19), which was nearly 2 weeks shorter.

▲Professor Jin-Hoon Chung (center) of the Department of Obstetrics and Gynecology at Asan Medical Center is performing a cesarean section for the delivery of twins.

Moreover, according to the team’s analysis, the preterm birth rate before 34 weeks of pregnancy was 10.8% for those who did not undergo cervical cerclage, while it was 42.1% for those who did, nearly 3.9 times higher. The incidence of chorioamnionitis, a condition that can harm both the fetus and mother, including neonatal infection and, in severe cases, neonatal brain injury and maternal sepsis, was 33.3% in mothers who underwent cervical cerclage, compared to only 9.7% in the non-cerclage group.

This study was supported by the Multiple Gestation Research Society of the Korean Society of Maternal Fetal Medicine and was recently published in the ‘Journal of Maternal-Fetal & Neonatal Medicine.’