The irritable uterus: A risk factor for preterm birth?

OBJECTIVE: Our aim was to determine the incidence and preterm delivery rate along with the indication for delivery in patients with uterine irritability. STUDY POPULATION: In this retrospective, descriptive study, 17,186 patients with well-defined high-risk factors were compared with 2637 women with uterine irritability. RESULTS: The incidence of preterm labor in patients with uterine irritability was 18.7%, significantly less than in those with other high-risk factors (odds ratio 0.35, 0.31 < odds ratio < 0.38). However, women with uterine irritability who experience preterm labor, compared with other high-risk factors, are much more likely to deliver before 34 weeks' gestation (odds ratio 2.50, 2.07 < odds ratio < 3.03) and more than twice as likely to deliver as a result of advanced preterm labor or membrane rupture (odss ratio 2.20, 1.75 < odds ratio < 2.78). CONCLUSIONS: The incidence of preterm labor in women with uterine irritability is not as frequent as in patients with other high-risk factors. However, preterm labor does occur in patients with uterine irritability at a rate higher than that in the general obstetric population (18.7% vs 11.0%). Because it appears that women with uterine irritability have more resistance to conventional tocolytic therapy, this condition should prompt the physician to use more aggressive perinatal assessment.