Verify the safety and effectiveness of the cerclage pessary in the prevention and treatment of high-risk preterm pregnancy.
Women with a pregnancy and a history of at least one spontaneous preterm birth before 34+0 weeks and/or a history of late abortion
12+0 -18+0 weeks of gestation
Minimal age of 18 years
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The previous preterm delivery is iatrogenic proterm labor
Major fetal abnormalities (requiring surgery or leading to infant death or severe handicap)
The pregnant woman with severe cervical erosion, cervical polyp, hemorrhage and the doctors think she could not use cerclage pessary
The pregnant woman with uterine cervicitis