Association of maternal IL-1 receptor antagonist intron 2 gene polymorphism and preterm birth

Objective This study was undertaken to determine whether the interleukin-1 receptor antagonist (IL-1RN) variable number tandem repeat polymorphism is associated with preterm birth. Study design A case–control study was performed. Cases (n = 95) delivered before 37 weeks after preterm labor (PTL) or preterm premature rupture of membranes (PPROM) and controls (n = 105) delivered after 37 weeks. Maternal DNA was genotyped by polymerase chain reaction for a length polymorphism in intron 2 of the IL-1RN gene. Results There was no significant difference in maternal age, ethnicity, insurance status, or parity between groups. Allele and genotype frequencies did not differ significantly from that expected under Hardy-Weinberg equilibrium (P = .59) in the total group as well as study groups. Of the 95 cases, 26.8% had at least 1 copy of allele 2 present compared with 12.4% in the control group (P< .0004). Conclusion Maternal carriage of at least 1 copy of the IL-1RN allele 2 appears to be associated with increased risk of preterm birth.