Can white blood cell count predict preterm delivery in women with vaginal bleeding between 20-37 weeks gestation?

VAGINAL BLEEDING BETWEEN 20-37 WEEKS GESTATION? MICHAEL WHITE, THOMAS TREVETT JR, WATSON BOWES, ROBERT STRAUSS, University of North Carolina at Chapel Hill, Obstetrics and Gynecology, Chapel Hill, North Carolina OBJECTIVE: To determine whether white blood cell count (WBC) is predictive of preterm delivery (PTD) in women admitted with vaginal bleeding between 20-37 weeks. STUDY DESIGN: This was a retrospective cohort study of all women who were admitted to the University of North Carolina Hospitals with documented vaginal bleeding from 20-37 weeks gestation from 1996 to 2003. Women were excluded if there was evidence of placenta previa or preterm rupture of membranes. Potential risk factors for preterm delivery were extracted from the medical records. Clinical and laboratory factors were assessed at time of presentation. A multivariable logistic regression analysis was used to create odds ratios (OR) and 95% confidence intervals (CI). RESULTS: 105 patients met inclusion criteria for analysis. The risk of PTD in this cohort before 32 and 37 weeks gestation was 32 and 82%, respectively. History of preterm delivery and tobacco use in pregnancy were included in the final model although these variables did not prove to be significant. Predictors of preterm birth included race, white blood cell count, hematocrit, and systolic blood pressure. After controlling for possible confounding variables, for each 1unit increase in WBC, the risk of delivery prior to 37 weeks increased by an OR of 1.32 (95% CI 1.06-1.69). CONCLUSION: Women presenting with unexplained vaginal bleeding who have elevated WBC at initial evaluation are at increased risk of preterm delivery.