Cervicovaginal prolactin: a marker for spontaneous preterm delivery

Our purpose was to determine whether the presence of prolactin in cervicovaginal washings is associated with preterm birth.

A cohort of 80 patients underwent a washing of the ectocervix and vaginal fornices with a normal saline solution. The cohort consisted of two groups: 40 inpatients requiring tocolysis and 40 asymptomatic outpatients. The saline solution aspirates were centrifuged, the supernatant was stored at -70 degrees C, and a radioimmunoassay for prolactin was run in batch fashion. A prolactin concentration greater than the detection limit of the assay was considered a positive test result.

Prolactin was identified in significantly more symptomatic patients than asymptomatic controls (50% vs 5%, p < 0.0001). In symptomatic patients cervicovaginal prolactin had an 80% positive predictive value and a 65% negative predictive value for delivery at < or = 34 weeks' gestation. Patients testing positive for prolactin had significantly shorter latency from testing to delivery (16 +/- 17 vs 34 +/- 24 days, p = 0.02) and had significantly lower birth weights (1985 +/- 729 vs 2583 +/- 696 gm, p = 0.01) compared with patients testing negative. Prolactin was also identified in two asymptomatic patients, both of whom were delivered before term.

Cervicovaginal prolactin is a biochemical marker for preterm delivery, a shorter latency period to delivery, and lower birth weight in symptomatic patients. This test may also prove to be a valuable marker for preterm birth in asymptomatic women.