Polymorphisms in methylenetetrahydrofolate reductase and pregnancy outcomes after in vitro fertilization

Abstract

OBJECTIVE: Studies on potential factors influential in recurrent pregnancy loss have suggested a possible association with inherited thrombophilias. Dysfunction of methylenetetrahydrofolate reductase (MTHFR) due to polymorphic genotypes may lead to elevated homocysteine levels, a condition that has been associated with increased risk of thrombotic events. The role of thrombophilia in recurrent early pregnancy loss is still uncertain and a controversial subject of contemporary research interest. In particular little is known regarding the effect of MTHFR polymorphisms on implantation. We sought to determine the potential relationship of different MTHFR genotypes with pregnancy outcomes from in vitro fertilization. The main objective was to determine whether MTHFR mutations have any effect on pregnancy rates. DESIGN: A retrospective cohort analysis of all patients who underwent in vitro fertilization at a private infertility office from January 2006 to December 2007 was performed. MATERIALS AND METHODS: IRB approval was obtained to perform a retrospective cohort analysis of all patients who underwent in vitro fertilization at a private infertility office from January 2006 to December 2007 was performed. Additional outcomes studied included detection of a gestational sac on ultrasound, ovulation induction and embryo characteristics, pregnancy loss, and live birth rates. One-way analysis of variance (ANOVA), Student's t-test and multivariate regression analysis were done using Stata10 adjusting for potential confounders. Chi-square and Fisher's exact statistic were used where appropriate. RESULTS: A total of 216 patients undergoing IVF and tested for MTHFR were identified in this cohort with 7.4% diagnosed with RPL. In our cohort among those with the diagnosis of RPL, the most common MTHFR genotype was heterozygous A1298C (6 of 16 patients with diagnosis of RPL). MTHFR wild type had an achieved pregnancy rate of 66% per cycle and having any polymorphism resulted in an achieved pregnancy rate of 73% per cycle overall (p=0.33). No difference was seen when stratified by each genotype. CONCLUSIONS: Polymorphisms in MTHFR do not appear to affect pregnancy rates following IVF as determined by a detectable serum β-hCG.