Which marker is used to predict imminent preterm labor by detecting a membrane-associated protein in the cervix?

• A. Inhibin A
• B. AFP
• C. Fetal fibronectin
• D. Human chorionic gonadotropin

Answer: (C)

Fetal fibronectin is the marker used to predict imminent preterm labor. It is a membrane-associated glycoprotein produced by the fetal membranes that normally helps attach the membranes to the decidua. When the membranes are at risk of separation or inflammation occurs, fetal fibronectin can leak into the cervicovaginal secretions and be detected with a rapid test. A positive result in the typical testing window (roughly 22–34 weeks) in a symptomatic woman indicates a higher likelihood of delivery within the near term (often within 7–14 days), guiding management such as steroids administration or closer monitoring. A negative result provides strong reassurance that delivery is unlikely in the short term. The other markers listed serve different purposes in prenatal screening and diagnosis (inhibin A for aneuploidy screening, AFP for neural tube defects, hCG for pregnancy confirmation), not for predicting imminent preterm birth via a cervicovaginal test.