Risk factors for spontaneous preterm delivery after arrested episode of preterm labor

Abstract

Introduction: We aimed to identify specific risk factors for spontaneous preterm delivery (PTD) among women with arrested preterm labor (PTL).Method: A retrospective study of women admitted due to imminent PTL and intact membranes, which did not progress to PTD within 24 h from admission. Eligibility was limited to singleton gestations at 24 + 0/7–33 + 6/7 weeks of gestations with no known chromosomal or structural anomalies. All women were treated with corticosteroids and tocolysis. Comparison was made between those who delivered at <37 + 0/7 weeks of gestation (study group) to women who delivered at ≥37 + 0/7 weeks of gestation (controls).Results: Overall, 301 women were recruited, of which 85 (28.2%) delivered before 37 + 0/7 weeks and 216 (71.8%) delivered at term. Advanced cervical dilatation was found to be an independent risk factor for PTD [for women with no past PTD: adjusted odds ratio (aOR) 1.66, 95% CI: 1.06–2.61 for each 1 cm dilatation; for women with past PTD: aOR 2.81, 95% CI: 1.02–7.73 for each 1 cm dilatation]. Among women without past PTD, additional independent risk factors for PTD were earlier gestational week at admission (OR: 1.20, 95% CI: 1.09–1.32 for each earlier week) and short cervical length (OR: 1.04, 95% CI: 1.01–1.08 for each decrease of 1 mm in cervical length).Conclusion: Advanced cervical dilatation, earlier gestational age at the episode of arrested PTL, and short cervical length are specific risk factors for PTD in women with arrested PTL. These findings may assist in counseling women and direct further investigation.