233 234 COMPARISON OF MULTIFETAL PREGNANCIES RESULTING FROM IN VITRO FERTILIZATION AND SPONTANEOUS CONCEPTION: DIFFERENCES IN MATERNAL INTERLEUKIN-1 RECEPTOR ANTAGONIST GENOTYPE DISTRIBUTION ROBIN B. KALISH, SANTOSH VARDHANA, MERUKA GUPTA, SRIRAM C. PERNI, STEVEN WITKIN, Weill Medical College of Cornell University, Obstetrics and Gynecology, New York, NY OBJECTIVE: To determine whether genotype frequencies of polymorphic genes associated with inflammation differed between women who conceived following in vitro fertilization (IVF) and women with spontaneously conceived multifetal pregnancies. STUDY DESIGN: Buccal swabs were obtained from 101 women with twin (98) or triplet (3) pregnancies. DNA was assayed by polymerase chain reaction for a length polymorphism in intron 2 of the IL-1ra gene and polymorphisms at position +3953 in the IL-1b gene, -590 in the IL-4 promoter, -1082 in the IL-10 promoter, and -308 in the TNF-a promoter. Patient charts were reviewed to obtain pregnancy outcomes. RESULTS: Multifetal pregnancies resulting from IVF occurred in 58 women; 43 women had spontaneous conceptions. IL-1ra homozygotes (IL1RN*1/IL1RN*1) were identified in 31.6% of women who underwent IVF as opposed to 52.5% with spontaneous conceptions (P = .06; OR = 0.42, 95% CI = 0.2-1.0). Conversely, the IL1RN*1/IL1RN*2 heterozygote genotype was present in 54.4% of women who underwent IVF as opposed to 27.5% of those with spontaneous conceptions (P = .01; OR = 3.14, 95% CI = 1.2-8.2). The IL-1ra genotype distribution was similar to that found in non-pregnant women only in the women with spontaneous conceptions. There were no differences in IL-1b, IL-4, IL-10, or TNF-a genotypes between the two groups. Similarly, the rate of spontaneous preterm birth was comparable in both groups. Volume 189, Number 6 Am J Obstet Gynecol SMFM Abstracts S127