Insulin-like growth factor-binding protein-1 in cervical secretion as a predictor of preterm delivery

Background. The aim of the study was to evaluate whether the phosphorylated isoforms of insulin-like growth factor-binding protein-1 (IGFBP-1), a protein produced by the decidua, can be detected in cervical secretions of pregnant women with preterm uterine contractions, and whether their presence predicts an increased risk of preterm delivery. Methods. A prospective analysis of sixty-three women who presented with preterm labor but intact fetal membranes at weeks 22-36+6 days of gestation at the Antenatal clinic at the Department of Obstetrics and Gynecology, Helsinki University Central Hospital. Phosphorylated IGFBP-1 (phIGFBP-1) was measured in cervical swab samples obtained at presentation, using an immunoenzymometric assay. The values greater than or equal to 10 mug/L were considered as positive. In addition, 58 asymptomatic women at the same gestational stage were studied as controls. Multiple logistic regression was applied to control for confounding variables and to obtain adjusted odds ratios. Results. The concentration of phIGFBP-1 in cervical samples ranged from undetectable to 95 mug/L. In 17 of the 63 (27%) women with preterm labor it was greater than or equal to 10 pg/L. Seven of these 17 (41%) women with a positive phIGFBP-1 result delivered preterm, all before 35 weeks of gestation. Among the women with preterm labor and a negative phIGFBP-1 result, three of the 46 (7%) delivered before 37 weeks of gestation (adjusted OR 24, 95% CI 1.2-487), but all after 35 weeks of gestation. In the asymptomatic control population three out of 58 (5%) women had a positive cervical phIGFBP-1 test result but none delivered preterm. Among the controls with a negative cervical phIGFBP-1 test result (55 of 58, 95%), one woman delivered preterm (1 of 55, 2%). Conclusions. Pregnant women who are in preterm labor with intact fetal membranes and who have a positive phIGFBP-1 test result in cervical secretion have an increased risk of preterm delivery.