Objective: We assessed the relationship between interleukin-6 (IL-6) promoter -174 polymorphism and spontaneous preterm birth (sPTB) less than 34 weeks and the relationship of polymorphism status with race.
Study design: Polymerase chain reaction was used to evaluate DNA from 156 controls who delivered after spontaneous labor at term and 51 subjects who had sPTB less than 34 weeks.
Results: Among the 156 controls, the C/C variant was present in 30 (19.2%). Among the 51 subjects, the C/C variant was present in 2 (6.3%) (odds ratio 0.17, 95% CI 0.04-0.74). Among white women, the C/C variant was present in 30 (27.2%) controls but only 2 (5.2%) cases. No African American women carried the C/C variant. The racial disparity was statistically significant. (P<.001)
Conclusion: The IL-6 promoter -174 allelic variant C/C is significantly less frequent among women with sPTB less than 34 weeks. There is a dramatic racial disparity in the distribution of allelic variants of this polymorphism.