Does fetal fibronectin testing prevent preterm birth?

FINDINGS:

In a systemic review and meta-analysis, the authors assessed 6 high quality randomized clinical trials to determine whether the use of fetal fibronectin (FFN) in the clinical setting actually reduces preterm labor. Berghella and Saccone (AJOG, 2016) compared 546 singleton gestations that were randomized to management based on FFN results (intervention group) or not (comparison group). When comparing the intervention to the control group, the researchers found:

No differences in

  • Labor incidence at <37 weeks, <34 weeks <32 weeks and <28 weeks gestation
  • Number of women who delivered within 7 days
  • Mean gestational age at delivery
  • Rate of maternal hospitalization
  • Use of tocolysis or antenatal steroids
  • Mean time in the triage unit
  • Neonatal outcomes, including RDS, admission to the NICU

Statistical difference was identified in

  • Cost of hospitalization charges with a mean additional cost of $153 in the intervention group (95% CI, 24.01 – 281.99)

SYNOPSIS:

FFN is an extracellular matrix glycoprotein produced during pregnancy by amniocytes and cytotrophoblasts. Studies have shown that increased levels of FFN in vaginal and cervical secretions are associated with spontaneous preterm birth (SPTB). Obtaining FFN is easy and safe, using a swab, and FFN has been used to help providers determine whether to keep patients with symptoms of SPTB under surveillance. While clinical validity has been determined – increased FFN levels are associated with SPTB – this meta-analysis sought to determine clinical utility and whether outcomes are altered in a positive way.

KEY POINTS:

  • Based on the findings of this paper, it appears that there is no clinical benefit but there are increased costs to the use of FFN in the management of singleton pregnancies with symptoms suggestive of SPTB
  • An editorial by GA Macones, MD, advocates that based on the findings in this study, the use of FFN testing in treated preterm labor is not justified
  • Studies that included the use of ultrasound measurement of cervical lengths were not included
  • Strengths of study include rigorous adherence to principles of evidence-based medicine, thereby reducing sources of bias
  • Limitations relate to the number of study subjects, and therefore stratification based on more individualized or particular clinical scenarios could not be assessed

Learn More – Primary Sources:

AJOG: Fetal fibronectin testing for prevention of preterm birth in singleton pregnancies with threatened preterm labor: a systematic review and meta-analysis of randomized controlled trials.

AJOG Editorial: Fetal fibronectin testing in threatened preterm labor: time to stop