Cervical insufficiency is defined as painless dilatation of the cervix during the second trimester of pregnancy. As a result of shortening and opening of the cervix, despite the lack of uterine contractions, the fetal membranes invade into the cervical canal and then into the vagina, which results in premature rupture of the membranes and miscarriage or preterm delivery. Cervical insufficiency occurs in approximately 1% of the women. The aim of the study is to evaluate the effectiveness of placing a double-level cervical cerclage in the treatment of advanced cervical insufficiency. The hypothesis assumes that the insertion of a double-level suture is associated with a reduction in the rate of deliveries < 34 weeks of gestation in comparison to single-level suture. The study will include women with fetal membranes visible through open external os of the cervix between 16+0 and 25+6 weeks. They will be randomized to two arms - McDonald's single cervical cerclage or two-level cerclage.

This is an open-label, multicentre, prospective, randomised controlled trial (RCT). Women will be randomized to the single-level cerclage arm or the double-level cerclage. Each patient will have a vaginal swab for aerobic and anaerobic bacteria and fungi culture, as well as for mycoplasmas, chlamydia and ureaplasma performed. Each patient will be treated with progesterone (vaginally 2 x 100 mg per day) and empirical antibiotic therapy (ceftriaxone 2.0 g iv + clarithromycin 2 x 500 mg po + metronidazole 3 x 500 mg iv for 7 days). If specific pathogens will be detected, the antibiotic therapy will be modified according to the antibiogram. If the diagnosis of cervical insufficiency will be made >23 weeks of gestation a single course of corticosteroid therapy will be administered (betamethasone 2 x 12 mg im) if the rsik of delivery within 7 days will be assessed as high. Indomethacin will also be administered for 48 hours (starting the day of cerclage administration, indomethacin 2 x 75 mg po for 48 hours). In the single-level cerclage arm McDonald suture will be administered. In the double-level cerclage arm two separate sutures analogous to McDonald technique will be placed, one approximately 1 cm higher above the other. Patients will be followed up until miscarriage or delivery and will receive standard perinatal care. Gestational age at delivery, the occurrence of cerclage complications and neonatal outcomes will be analyzed.

Inclusion Criteria:

• singleton pregnancy,
• gestational age 16+0 to 25+6 weeks,
• live fetus,
• cervical incompetence with fetal membranes visible through external os before 24+0 weeks of gestation,
• informed written consent.

Exclusion Criteria - any of the following occuring before the administration of the cerclage:

• preterm premature rupture of membranes,
• vaginal bleeding,
• active regular uterine contractions,
• fetal demise,
• fever,
• intrauterine infection (diagnosed in case of maternal body temperature ≥ 38°C with no alternative cause identified and at least 2 symptoms among the following appear: fetal tachycardia > 160 bpm for 10 minutes or longer, uterine pain, purulent vaginal discharge, white blood cell count > 15 G/L in the absence of corticosteroid treatment or increased plasma C-reactive protein > 10 mg/L),
• known genetic defects of the fetus,
• known lethal fetal malformations,
• congenital uterine defects,
• multiple pregnancy.

Female - pregnant women

IPD share with other researchers will include all IPD that underlie results in a publication

Data will become available after completing of recruitment and will be available for 12 months

Data will be available od request sent to the principal researchers. All requests for information will be reviewed by the Study Officials.