Please select the eligibility criteria that correspond to the clinical trial below.
Title: Pessary in Singleton Gestations With Short Cervix Without Prior Preterm Birth
Brief Summary: Spontaneous preterm birth (SPTB) remains the number one cause of perinatal mortality in many countries, including the United States. In singleton gestations a short cervical length (CL) on transvaginal ultrasound (TVU) has been shown to be a good predictor of SPTB.

The cervical pessary is a silicone device that has been used to prevent SPTB. The efficacy of cervical pessary has been assessed in several populations including singletons with short CL, unselected twins, twins with a short CL, and triplet pregnancies. Several randomized clinical trials (RCTs) have been published, and several are ongoing. However, no consensus on the use of cervical pessary in pregnancy or guidelines for management have been assessed.


Options:
A: Inclusion Criteria:

* 18-50 years of age
* Singleton pregnancy (limits the participants to female gender)
* Short cervical length (less than or equal to 25 mm) on second trimester ultrasound at 18-23 6/7 weeks gestation

Exclusion Criteria:

* Multiple gestation
* Prior spontaneous preterm birth 16-36 6/7 weeks
* Ruptured membranes
* Lethal fetal structural anomaly
* Fetal chromosomal abnormality
* Cerclage in place (or planned placement)
* Vaginal bleeding
* Suspicion of chorioamnionitis
* Ballooning of membranes outside the cervix into the vagina or CL = 0 mm on transvaginal ultrasound
* Painful regular uterine contractions
* Placenta previa
B: 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
C: Inclusion Criteria:

* Pregnant women with short cervix (=\< 25 mm) identified by use of routine transvaginal ultrasonography at 19-22 weeks of gestation.
* Single pregnancy
* Women older than 18 year-old
* Women sign informed consent according GCP and local legislation
* Gestational age at randomization between 20+1 and 23+6 weeks.

Exclusion Criteria:

* Major fetal abnormalities
* Major uterine abnormalities
* Placenta praevia during current pregnancy
* Vaginal bleeding or ruptured membranes in the moment of randomization
* Cervical cerclage in situ
* History of cone biopsy
* Allergic to peanuts
* Contraindication for Progesterone usage.
* Active treatment with Progesterone at randomization.
* History of 3 or more premature labor.
* If in the investigator's opinion, there are findings on physical examination, abnormalities in the results of clinical analyzes or other medical factors, social or psycho-social that could negatively influence.
* Women unable to give the informed consent
D: Inclusion Criteria:

* 18-50 years of age
* Singleton pregnancy (limits the participants to female gender)
* Short cervical length (less than or equal to 25 mm) on second trimester transvaginal ultrasound at 18-23 6/7 weeks gestation

Exclusion Criteria:

* Multiple gestation
* Prior spontaneous preterm birth 16-36 6/7 weeks
* Ruptured membranes
* Lethal fetal structural anomaly
* Fetal chromosomal abnormality
* Cerclage in place (or planned placement)
* Vaginal bleeding
* Suspicion of chorioamnionitis
* Ballooning of membranes outside the cervix into the vagina or CL = 0 mm on transvaginal ultrasound
* Painful regular uterine contractions
* Placenta previa

Answer: D