Objective: To assess efficacy of cervico-vaginal fetal fibronectin as a predictor of spontaneous preterm birth in a high risk antenatal population, and to evaluate the psychological impact of fetal fibronectin testing.
Design: An observational study.
Setting: The antenatal clinic at a tertiary referral hospital.
Population: One hundred and forty-six pregnant women with known risk factors for spontaneous preterm birth.
Methods: Women designated as 'at risk' for preterm delivery by clinical history were screened for fetal fibronectin at 24 and again at 27 weeks of gestation. Anxiety levels were assessed by questionnaire and compared with anxiety levels of 206 low risk women also tested for fetal fibronectin. Fetal fibronectin results were disclosed to the woman and her clinician.
Main outcome measures: Maternal anxiety and efficacy of the 24-week fetal fibronectin test to predict delivery before 30, 34 and 37 weeks of gestation.
Results: Maternal anxiety was higher pretesting in those at high risk compared with low risk women undergoing the test. Among the high risk women, anxiety was raised to clinically significant levels in those receiving a positive fetal fibronectin screening test result. In all women, 5%, 9% and 21% delivered <30, <34 or <37 weeks of gestation, respectively. Nine percent (n= 13) tested positive for fetal fibronectin at 24 weeks. Predictive power for fetal fibronectin (24 weeks) was greatest for delivery <30 weeks of gestation, with a likelihood ratio of 15 for a positive test (6/13 positive women delivered before 30 weeks).
Conclusions: Fetal fibronectin was most efficient as a predictor of preterm spontaneous delivery <30 weeks of gestation, but was associated with high levels of anxiety.