Please select the eligibility criteria that correspond to the clinical trial below.
Title: Verify the Safety and Effectiveness of the Cerclage Pessary in the Prevention and Treatment of High-risk Preterm Pregnancy
Brief Summary: Verify the safety and effectiveness of the cerclage pessary in the prevention and treatment of high-risk preterm pregnancy.


Options:
A: Inclusion Criteria:

* Women with a singleton pregnancy and a history of at least one previous preterm delivery before 34+0 weeks and/or a history of at least one previous cervical surgery
* 12+0 - 16+0 weeks of gestation at time of randomization
* only women with minimum age of 18 and capable of giving consent

Exclusion Criteria:

* major fetal abnormalities
* uterine malformation, placenta previa totalis
* Cerclage prior to randomization
* At randomisation: active vaginal bleeding and/or spontaneous rupture of membranes and/or painful regular uterine contractions
* silicone allergy
* current participation in other RCT
B: Inclusion Criteria:

* Diagnosed to be pregnant at up to 24+0 weeks of gestation, with a cervical length measurement of ≤25 mm with a singleton pregnancy, or ≤38 mm in twins pregnancy.
* Does not meet with maternal/fetal/membrane/placental factors detailed in the exclusion criteria.
* Willingness to comply with the protocol for the duration of the study.
* Have signed an informed consent.

Exclusion Criteria:

* Fetal factors: major fetal abnormalities, death of one or both of the fetuses, twins- twin-to-twin transfusion syndrome, and severe growth retardation.
* Maternal factors: prophylactic cervical cerclage in situ, painful regular uterine contractions, active labor, active vaginal bleeding, maternal age under 18, uterine abnormalities (i.e. two cervices), and severe uterine prolapse.
* Membranes and placental factors: placenta previa, ruptured membranes.
C: Inclusion Criteria:

* 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
* Informed consent signature

Exclusion Criteria:

* 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
* The pregnant woman that has been confirmed premature birth
* Cerclage prior to randomisation
* Cerclage prior to randomisation
* Placenta previa totalis
* Active vaginal bleeding at the moment of randomization
* Spontaneous rupture of membranes at the time of randomization
* Silicone allergy
* Painful regular uterine contractions
* The pregnant woman have the indication of operation cervical cerclage
* Current participation in other RCT
D: Inclusion Criteria:

* patient with a short cervix equal to or less than 25 mm by transvaginal ultrasound
* gestational age between 18 (0/7) and 23 (6/7) weeks of gestation according to the results of the ultrasound of the first trimester, or by integrating the date of the last period
* patients who were informed of the study and agreed to sign the consent form.

Exclusion Criteria:

* pregnancy with a fetus with a major congenital malformation - regular and painful uterine activity - history of preterm premature rupture of membranes (PPROM) - active vaginal bleeding - complete and incomplete placenta previa - cerclage of the cervix in place - antecedent of conisation - multiple gestation - ballooning of membranes outside the cervix into the vagina - allergy/intolerance or hypersensitivity to progesterone or any of its ingredients - chronic medical conditions that would interfere with study participation or evaluation of treatment - vaginal administration of another drug.

Answer: C