Jd. Iams et al., FETAL FIBRONECTIN IMPROVES THE ACCURACY OF DIAGNOSIS OF PRETERM LABOR, American journal of obstetrics and gynecology, 173(1), 1995, pp. 141-145
OBJECTIVE: Our purpose was to assess the utility of cervicovaginal exp
ression of fetal fibronectin in the diagnosis of preterm labor. STUDY
DESIGN: Women seen between 24 and 34 weeks' gestation with symptoms of
preterm labor, intact membranes, and cervical dilatation <3 cm were e
nrolled at five university medical centers. Cervicovaginal swabs were
obtained and assayed for the presence of fetal fibronectin by means of
a monoclonal antibody assay. Results were compared with cervical dila
tation and uterine contraction frequency as indicators of interval to
delivery and delivery before 37 weeks. RESULTS: A total of 192 eligibl
e women at a mean gestational age of 30.8 a 2.9 weeks were enrolled fr
om a population of 418 subjects screened. The rate of preterm birth wa
s 32.3% (62/199). The mean interval from presentation to delivery was
25.3 +/- 24.1 days in the 45 subjects with a positive fibronectin assa
y and 52.4 +/- 24.8 days in the 147 subjects with a negative assay (p
= 0.0001). The sensitivity, specificity, and positive and negative pre
dictive values of fetal fibronectin expression for delivery <37 weeks
were 44% (27/62), 86% (112/130), 60% (27/45), and 76% (112/147). The f
etal fibronectin assay was especially useful in predicting risk of del
ivery within 7 days (sensitivity 93% [13/14], specificity 82% [146/178
], positive predictive value 29% [13/45], and negative predictive valu
e 99% [146/147]) and was notably superior to both cervical dilatation
>1 cm and contraction frequency greater than or equal to eight per hou
r (sensitivities 29% and 42%, specificities 82% and 67%, positive pred
ictive values 11% and 9%, and negative predictive values 94% and 94%,
respectively). CONCLUSION: Cervicovaginal fetal fibronectin predicts d
elivery within 7 days more accurately than do cervical dilatation and
contraction frequency in a population of women evaluated for early pre
term labor.