Which marker increases in preterm labor and delivery?

• A. Amniotic fluid lactate
• B. D-dimer
• C. Fetal fibronectin (fFN)
• D. hCG

Answer: (C)

Fetal fibronectin in vaginal secretions is a biomarker used to assess the risk of imminent preterm delivery. It helps indicate disruption at the choriodecidual interface as labor approaches. When symptoms of preterm labor appear between about 22 and 34 weeks, a positive fFN test suggests a higher likelihood of delivery within the next 7–14 days, guiding management decisions. A negative result is especially reassuring, indicating a low short-term risk of preterm birth.

Amniotic fluid lactate can rise with intra-amniotic infection but is not a specific predictor of preterm labor. D-dimer reflects coagulation activity and placental pathology rather than impending labor, and hCG is the early-pregnancy hormone not used to forecast preterm birth.