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

OBJECTIVE: Granulocyte colony-stimulating factor is elevated in the amnioti c fluid and plasma of women with chorioamnionitis and active preterm labor. We investigated the relationship between plasma granulocyte colony-stimula ting factor and subsequent spontaneous preterm birth in pregnant women with out 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 Predictio n Study. Plasma collected at 24 and 28 weeks' gestation was analyzed for gr anulocyte colony-stimulating factor, and the results were compared with sub sequent spontaneous preterm birth. RESULTS: Compared with term control subjects, women who were delivered of t heir infants spontaneously at <28 weeks' gestation had increased mean granu locyte colony-stimulating factor values at 24 weeks' gestation (84.7 +/- 38 .4 vs 67.7 +/- 28.6 pg/mL; P=.049), and women who were delivered of their i nfants at <32 weeks' gestation had increased mean plasma granulocyte colony -stimulating factor Values at 28 weeks' gestation (80.4 +/- 24.1 vs 55.9 +/ - 16.5 pg/mL; P =.001). At 24 weeks' gestation a granulocyte colony-stimula ting factor value >75th percentile in control subjects (approximately 80 pg /mL) was found in 48.9% (23/47) of all women delivered of their infants at <32 weeks' gestation versus 14.9% (7/47) of the term control subjects (adju sted odds ratio. 6.2; 95% confidence interval, 1.8-20.8). At 28 weeks' gest ation a granulocyte colony-stimulating factor value >75th percentile was fo und in 36.8% (7/19) of women delivered of their infants at <32 weeks' gesta tion 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 weeks' ges tation, granulocyte colony-stimulating factor did not predict spontaneous p reterm birth at 32 to 34 weeks' gestation or at 35 to 36 weeks' gestation. CONCLUSION: In pregnant women without symptoms at 24 and 28 weeks' gestatio n, elevated plasma granulocyte colony-stimulating factor levels are associa ted with subsequent early (32 weeks' gestation) spontaneous preterm birth, especially within the next 4 weeks, but not with late spontaneous preterm b irth. These data provide further evidence that early spontaneous preterm bi rth is associated with an inflammatory process that is identifiable by the presence of a cytokine in maternal plasma several weeks before the early sp ontaneous preterm birth; however, later spontaneous preterm birth is not as sociated with this process.