Routine cervical length and fetal fibronectin screening in asymptomatic twin pregnancies: Is there clinical benefit?

Objective: To determine whether routine cervical length (CL) and fetal fibronectin (fFN) screening is associated with improved clinical outcomes in asymptomatic patients with twin pregnancies. Study design: We compared outcomes between two large cohorts of twin pregnancies who delivered in New York City from 2003 to 2012. One cohort (n=532) was managed by a single group practice, delivered at one large academic medical center, and underwent routine serial CL and fFN screening. The second cohort (n=456) delivered at a second large academic center and only underwent CL and fFN testing as clinically indicated. Outcomes measured include cerclage placement, preterm birth (PTB), spontaneous PTB (sPTB), and antenatal corticosteroid (ACS) exposure. Results: Rates of cerclage placement, PTB, and SPTB were similar between the two groups. However, routine CL and fFN screening was associated with improved rates of ACS exposure in patients who delivered <34 weeks (91.3% versus 74.7%, p=0.005) and 34-36 6/7 weeks (41.3% versus 13.9%, p<0.001) without increased ACS exposure in women who delivered at term. In patients who delivered <34 weeks, routine CL and fFN screening was significantly associated with improved rates of ACS exposure within 1-14 days of delivery and within 1-7 days of delivery. Conclusion: In twin pregnancies, routine CL and fFN screening does not reduce the risk of PTB or SPTB. However, the routine use of these tests is associated with significantly improved ACS exposure and timing for women who deliver preterm without increasing ACS exposure to women who deliver at term.