Fetal fibronectin and spontaneous preterm birth

• fetal fibronectin is a glycoprotein that, when absent in cervicovaginal secretions between 24-34 weeks gestation, indicates that a woman is unlikely to give birth within the next 7-14 day (1)
  • test, using a vaginal swab, is easy to perform and test results are rapidly available

Notes:

• fetal fibronectin
  • presence of fetal fibronectin is an effective biochemical marker for predicting preterm birth
  • a stable glycoprotein produced by the fetal membranes, adheres the fetal membranes and placenta to the uterine lining and plays a critical role in facilitating the physiological separation of the placenta from the uterus after delivery
  • generally not present at levels >50 ng/mL between 16 and 22 weeks of gestation, earlier studies have shown that its presence (>50 ng/mL) in the cervix or vagina from 22 weeks of gestation and beyond is a powerful predictor of subsequent spontaneous preterm birth (2,3)
    
    
• NICE state (4)
  • fetal fibronectin testing should be considered as a diagnostic test to determine likelihood of birth within 48 hours for women who are 30+0 weeks pregnant or more if transvaginal ultrasound measurement of cervical length is indicated but is not available or not acceptable. Act on the results as follows:
    • if fetal fibronectin testing is negative (concentration 50 ng/ml or less), explain to the woman that it is unlikely that she is in preterm labour and:
      • think about alternative diagnoses
      • discuss with her the benefits and risks of going home compared with continued monitoring and treatment in hospital
      • advise her that if she does decide to go home, she should return if symptoms suggestive of preterm labour persist or recur
    • if fetal fibronectin testing is positive (concentration more than 50 ng/ml), view the woman as being in diagnosed preterm labour and offer treatment measures for preterm labour (tocolysis, maternal corticosteroids)

Reference:

• Hepburn CM, Booth M. Fetal fibronectin testing in Ontario: successful government-sector collaboration to achieve high-quality and sustainable system change. Healthc Q. 2011;14:90-94
• Goldenberg RL et al.The Preterm Prediction Study: toward a multiple-marker test for spontaneous preterm birth. Am J Obstet Gynecol. 2001 Sep; 185(3):643-51
• Goldenberg RL, Klebanoff M, Carey JC, et al. Vaginal fetal fibronectin measurements from 8 to 22 weeks' gestation and subsequent spontaneous preterm birth. American Journal of Obstetrics and Gynecology. 2000;183(2):469-475.
• NICE (August 2019).Preterm labour and birth