Prevention of preterm birth

The rate of preterm birth at <34 weeks in singleton pregnancies is about 2% and in twin pregnancies the rate is 15%. In both singleton and twin pregnancies the rate of preterm birth is inversely related to cervical length at 20-24 weeks of gestation.

In twin pregnancies with a short cervix (<25 mm) diagnosed by routine transvaginal sonography at 20-24 weeks three strategies have been attempted to reduce the risk of preterm birth (PTB):

• Vaginal progesterone from 20-34 weeks may the rate of spontaneous PTB at <34 weeks by up to 30%.

• Cervical cerclage may increase the rate of spontaneous PTB at <34 weeks.

• Cervical pessary in unselected twin pregnancies does not reduce the rate of spontaneous PTB at <34 weeks.

1. Romero R, Conde-Agudelo A, El-Refaie W, Rode L, Brizot ML, Cetingoz E, Serra V, Da Fonseca E, Abdelhafez MS, Tabor A, Perales A, Hassan SS, Nicolaides KH. Vaginal progesterone decreases preterm birth and neonatal morbidity and mortality in women with a twin gestation and a short cervix: an updated meta-analysis of individual patient data. Ultrasound Obstet Gynecol 2017;49:303-314.
2. Nicolaides KH, Syngelaki A, Poon LC, de Paco Matallana C, Plasencia W, Molina FS, Picciarelli G, Tul N, Celik E, Lau TK, Conturso R. Cervical pessary placement for prevention of preterm birth in unselected twin pregnancies: a randomized controlled trial. Am J Obstet Gynecol 2016;214:3.e1-9.