What is the risk of preterm delivery after arrested preterm labor?

Objective The aim of this study is to assess if women with arrested preterm labor (PTL) have an increased risk of preterm delivery (PTD) compared with healthy pregnant women, and if digital examination, fetal fibronectin (fFn) and cervical length (CL) are prognostic markers for PTD after arrested PTL.

Study Design Prospective-matched cohort study among women with arrested PTL (cases) and healthy pregnant women (controls).

Results We included 74 index cases and 74 controls. PTD occurred in 20 (27%) index cases and in 5 (7%) controls (hazard ratio [HR], 4.5; 95% confidence interval [CI], 1.7-12). A dilatation of the cervix ≥ 1 cm (HR, 9.1 [95% CI, 3.3-25], an fFn positive status (HR, 13 [95% CI, 4.3-40]), and a CL < 15 mm (HR, 11 [95% CI, 3.1-38]) increased this risk in cases compared with controls. Knowledge of the fFn result had additional value over the cervical dilatation or CL in the prediction of persistent PTD, with an increased risk in case of a positive fFn test.

Conclusion Women stay at increased risk for PTD after arrested PTL. This risk further increased in case of ≥ 1 cm cervical dilatation, CL < 15 mm and/or a positive fFn status.