Diagnosis of labor: a prospective study.

Accurate diagnosis of the onset of labor remains a problem in obstetrics. Criteria commonly used to diagnose labor have never been scientifically evaluated. This prospective study involved 423 pregnant women who presented themselves with uterine contractions to 2 Italian hospitals (248 nulliparous patients total and 175 multiparous total) and who were either admitted or advised to return home. The obstetrician on duty collected data using a standardized form that listed common criteria for labor diagnosis. Multivariate analysis showed that a reduction of the interval between consecutive uterine contractions, odds ratio [OR] = 1.42; 95% confidence interval [95%CI] 1.06-1.90); abdominal pain of increasing intensity (OR = 1.42; 95% CI 1.01-2.02); cervical effacement (OR = 1.4; 95%CI 1.12-1.77); and cervical dilation (OR = 1.91; 95% CI 1.53-2.38) were significant markers of the onset of labor. On the other hand, backache had a negative diagnostic value (OR = 0.78; 95% CI 0.61-0.99). The value of criteria such as regular uterine contractions, loss of mucous plug, changes in intestinal habits, vomiting, pain that is relieved by walking, and changes in breathing pattern did not reach statistical significance.