[Predictive value of cervical-vaginal prolactin in the evaluation of premature labor risk]

To determine whether the presence of cervico-vaginal prolactin during pregnancy is significantly associated with preterm delivery.

A cohort of 64 pregnant women between 21 and 34 weeks of amenorrhea underwent a washing of the exocervix and vaginal fornices with a normal saline solution. The fluid was then aspirated and centrifuged. Samples were stored at -70 degrees C and later prolactin level was determined by radioimmunoassay. Test was considered as positive for a prolactin concentration higher than 2 ng/ml. Statistical analysis were realized by Student's t test, Fisher's exact test and chi 2 test.

In patients with preterm labor, positive cervico-vaginal prolactin had a positive predictive value of 36% and a negative predictive value of 94% for a preterm delivery before 34 weeks of gestation (respectively 45% and 79% before 37 weeks). The sensitivity of a positive test was 31% for preterm delivery before 37 weeks of gestation and specificity was 87% (respectively 57% and 88% before 34 weeks). Patients with a positive prolactin test had a significantly shorter latency between testing and delivery (33.7 days vs 52.4 days; p < 10(-9)). No delivery occurred during the following weeks for patients with a negative prolactin test and, among those, only one delivery occurred during the second week following the test. Positive prolactin tests correlated with a mean cervical dilatation of 1 centimetre at the time of testing, while it was of 0.6 centimetre for patients with a negative prolactin test.

Cervico-vaginal prolactin seems to be a non convincing marker for preterm delivery but indicative of a shorter latency from testing to delivery in symptomatic patients. Further investigations are necessary to evaluate accuracy of cervico-vaginal prolactin as a biochemical marker for imminent delivery in patients with preterm labor.