Placement of a vaginal pessary reduces significantly the rate of spontaneous preterm birth in pregnant women with twins and a short cervical length at 18-22 weeks scan.

This trial includes pregnant women with twins undergoing routine ultrasound examination at 18.0 to 22.6 weeks of gestation.

Inclusion Criteria:

• Twins
• Minimal age of 18 years

Exclusion Criteria:

• Major fetal abnormalities (requiring surgery or leading to infant death or severe handicap)
• Spontaneous rupture of membranes at the time of randomization
• Cervical cerclage in situ
• Active vaginal bleeding
• Placenta previa