Elevated levels of decidual insulin-like growth factor binding protein-1 in cervical fluid in early and mid-pregnancy are associated with an increased risk of spontaneous preterm delivery

Objective To study whether elevated levels of decidual insulin-like growth factor binding protein-1 (IGFBP-1) in the cervical fluid of unselected asymptomatic women in early or mid-pregnancy are associated with spontaneous preterm delivery (PTD). Design Prospective population-based cohort study. Setting Maternity Clinics, University Central Hospital, Helsinki, Finland. Population A total of 5180 unselected pregnant women. Methods Cervical swab samples were collected during the first and second trimester ultrasound screening. The concentration of IGFBP-1 was measured by immunoenzymometric assay, which detects the decidual phosphoisoforms of IGFBP-1 (phIGFBP-1). Concentrations of 10 micrograms/l or more were considered to be elevated. Main outcome measure Spontaneous PTD. Results In the first trimester, 24.5% of women, and in the mid-second trimester, 20.2% of women, had an elevated cervical fluid phIGFBP-1 level. The rates of spontaneous PTD before 32 and before 37 weeks of gestation were higher in women with an elevated cervical fluid phIGFBP-1 level, compared with women who had cervical phIGFBP-1 of < 10 micrograms/l (1.1% versus 0.3% and 5.7% versus 3.2%, respectively). An elevated phIGFBP-1 level in the first trimester was an independent predictor for PTD before 32 and before 37 weeks of gestation, with odds ratios of 3.0 (95% CI 1.3-7.0) and 1.6 (95% CI 1.2-2.3), respectively. Cervical phIGFBP-1 levels of 10 micrograms/l or more in the first trimester predicted PTD before 32 and before 37 weeks of gestation, with sensitivities of 53.8% and 37.0%, respectively. The negative predictive values were 99.7% and 96.8%. Conclusions Elevated cervical fluid phIGFBP-1 levels in the first trimester were associated with an increased risk of spontaneous PTD.