Fetal fibronectin--how useful is it in the prediction of preterm birth?

To determine the value of cervicovaginal fetal fibronectin as a marker for preterm delivery, a previously published meta-analysis was updated.

Selection criteria confined the analysis to English-language original reports of prospective studies including women at <37 weeks' gestation with intact amniotic membranes. For the outcomes of delivery <37 or <34 weeks' gestation or delivery within 7, 14, or 21 days after fibronectin sampling, we calculated sensitivity and specificity rates for each study, for subgroups of studies, and for all studies combined.

A total of 40 studies were included. Statistical heterogeneity was seen in the majority of calculations of combined results and a random-effects model was used in these cases. For the outcomes of delivery <37 and <34 weeks' gestation, overall sensitivity rates were 52% and 53%, and overall specificity rates were 85% and 89%, respectively. For the outcomes of delivery within 7, 14, and 21 days, we calculated sensitivity rates of 71%, 67%, and 59% and specificity rates of 89%, 89%, and 92%, respectively. For the subgroup of women with symptoms of preterm labour, sensitivity rates for delivery <37 and <34 weeks' gestation or delivery within 7, 14, and 21 days of 54%, 63%, 77%, 74%, and 70% and specificity rates of 85%, 86%, 87%, 87%, and 90% were calculated.

Cervicovaginal fetal fibronectin is an effective short-term marker of preterm delivery, especially in women with symptoms of preterm labour. Because results appear to be heterogeneous in different studies, caution should be taken when they are applied to a specific population.