Abstract Objective To find a biological marker associated with preterm delivery or neonatal infection in pregnant women with preterm labour and intact membranes. Study design Cervical secretions were collected from 286 women hospitalized for preterm labour with intact membranes at 24–34 weeks’ gestation. The outcomes studied were delivery before 33 and 35 weeks’ gestation, chorioamnionitis, and neonatal infection, and their association with the presence of IL-6 mRNA in cervical secretions as detected by RT-PCR. The other infectious markers tested were: bacterial vaginosis and fetal fibronectin in cervical secretions; serum CRP and white blood cell count. Results The vaginal secretions of 13 of 286 women (4.7%) contained IL-6 mRNA. The only other marker tested significantly associated with IL-6 mRNA+ was the presence of streptococcus in vaginal secretions (30.8% versus 9.4% in the IL-6+ and–groups, p = 0.03). Although the difference did not reach statistical significance ( p < 0.06 and 0.08, respectively), in women with IL-6 mRNA in cervical secretions we observed a tendency to give birth before 33 and 35 weeks more often than the population as a whole. This group was at higher risk of neonatal infection (38.5% versus 15.1%; p = 0.04). After adjustment for infectious risk factors, IL-6 remained significantly associated with neonatal infection (OR = 4.6, 95% CI [1.1–18.9]). The sensitivity of IL-6 mRNA for neonatal infection was 11.1%. The specificity was 96.7%. Conclusion The detection of IL-6 mRNA by RT-PCR in vaginal secretions allows identification of a small group of women at high risk of neonatal infection, independently of other markers of infection.