The Preterm Prediction Study: Granulocyte colony-stimulating factor and spontaneous preterm birth

Objective: Granulocyte colony-stimulating factor is elevated in the amniotic fluid and plasma of women with chorioamnionitis and active preterm labor. We investigated the relationship between plasma granulocyte colony-stimulating factor and subsequent spontaneous preterm birth in pregnant women without symptoms. Study Design: We performed a nested case-control study involving 194 women who had a singleton spontaneous preterm birth and 194 matched term control subjects from the patient pool (n = 2929) enrolled in the Preterm Prediction Study. Plasma collected at 24 and 28 weeksʹ gestation was analyzed for granulocyte colony-stimulating factor, and the results were compared with subsequent spontaneous preterm birth. Results: Compared with term control subjects, women who were delivered of their infants spontaneously at <28 weeksʹ gestation had increased mean granulocyte colony-stimulating factor values at 24 weeksʹ gestation (84.7 ± 38.4 vs 67.7 ± 28.6 pg/mL; P = .049), and women who were delivered of their infants at <32 weeksʹ gestation had increased mean plasma granulocyte colony-stimulating factor values at 28 weeksʹ gestation (80.4 t 24.1 vs 55.9 ± 16.5 pg/mL; P = .001). At 24 weeksʹ gestation a granulocyte colony-stimulating factor value >75th percentile in control subjects (appro)imately 80 pg/mL) was found in 48.9% (23/47) of all women delivered of their infants at <32 weeksʹ gestation versus 14.9% (7/47) of the term control subjects (adjusted odds ratio, 6.2; 95% confidence interval, 1.8–20.8). At 28 weeksʹ gestation a granulocyte colony-stimulating factor value >75th percentile was found in 36.8% (7/19) of women delivered of their infants at <32 weeksʹ gestation versus 5.3% (1/19) of term control subjects (adjusted odds ratio, 25.7; 95% confidence interval, 1.5–470.4). When measured at 24 or 28 weeksʹ gestation, granulocyte colony-stimulating factor did not predict spontaneous preterm birth at 32 to 34 weeksʹ gestation or at 35 to 36 weeksʹ gestation. Conclusions: In pregnant women without symptoms at 24 and 28 weeksʹ gestation, elevated plasma granulocyte colony-stimulating factor levels are associated with subsequent early (<32 weeksʹ gestation) spontaneous preterm birth, especially within the next 4 weeks, but not with late spontaneous preterm birth. These data provide further evidence that early spontaneous preterm birth is associated with an inflammatory process that is identifiable by the presence of a cytokine in matemal plasma several weeks before the early spontaneous preterm birth; however, later spontaneous preterm birth is not associated with this process.