Methods The study was conducted at five tertiary care university obstetric centers serving diverse populations in North America. The protocol was approved by the human subjects review board at each institution. Women who were seen for unscheduled obstetric care between 24 and 34 weeks’ gestation with complaints suggestive of preterm labor (e.g., suspected amniorrhexis, uterine activity, abdominal discomfort, change in vaginal discharge, bleeding, or cramping) were screened for eligibility. Gestational age was established by date of last menstrual period and confirmed by ultrasonography or was set by ultrasonography if menstrual dates were unreliable or discordant by > 10 days. All subjects gave informed consent at the time of screening in accordance with the institutional review board policies at each institution. After consent was obtained, each subject was examined with a vaginal speculum to collect specimens for fetal fibronectin determination and to assess the amniotic membranes. The diagnosis of preterm amniorrhexis was established by the presence of at least two of the three standard findings of pH 2’7, fern pattern of dried fluid, and vaginal pooling of amniotic fluid. Digital examination of the cervix was then performed. Women with confirmed ruptured membranes, cervical dilatation 2 3 cm, a cervical cerclage suture, uterine anomalies, placenta previa, or abruptio placentae were excluded. Treatment was not influenced by participation in the study. Results of the fetal fibronectin assay were not available for management.
Uterine