title: Prediction of preterm birth in twins.
abstract: About 13% of twins are born before 34 weeks and 7% before 32 weeks. The prediction of preterm birth in twins is based on the same tests as in singleton pregnancies. In twin pregnancies, the cut-off for short cervix at the second trimester scan is less than 25 mm (compared with 15 mm in singletons); length less than 20 mm is associated with 42% risk for birth before 32 weeks and cervical length less than 25 mm is associated with 28% risk for birth before 28 weeks. The measurement of cervical length in pregnancies with symptoms of preterm labour may have limited accuracy in predicting preterm birth. In asymptomatic women, a positive fetal fibronectin test seems to be associated with 35% risk for birth before 32 weeks and 40% risk for birth less than 34 weeks, whereas a negative test decreases the risk to 6% and 17%, respectively. The differences in the predictive value of tests between twins and singletons reflect the diverse pathophysiology of preterm birth between the two groups.
authors.affiliation: Department of Obstetrics and Gynaecology, University Hospital of Ioannina, Ioannina, Stavros Niarchos Avenue, 45500 Ioannina, Greece. Electronic address: grmak@otenet.gr.
authors.forename: George
authors.initials: G
authors.lastname: Makrydimas
authors.affiliation: Second Department of Obstetrics and Gynaecology, Aristotle University of Thessaloniki, Ippokrateio General Hospital, Thessaloniki, Greece.
authors.forename: Alexandros
authors.initials: A
authors.lastname: Sotiriadis
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis; D002584:Cervix Uteri / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D005353:Fibronectins / Q000032:analysis*; D006801:Humans; D007231:Infant, Newborn; D011237:Predictive Value of Tests; D011247:Pregnancy; D059285:Pregnancy, Twin; D047928:Premature Birth / Q000175:diagnosis* / Q000000981:diagnostic imaging; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014427:Twins; D016216:Ultrasonography, Prenatal
chemical_list: D015415:Biomarkers; C403421:FFN protein, human; D005353:Fibronectins
keywords: cervical length; fibronectin; preterm birth; twins; ultrasound