Homocysteine serum levels correlate with the number of failed IVF cycles even when within normal range

Introduction Repeated implantation failure is a common challenge in daily practice. Homocysteine and vitamin B12 have been associated with reproductive processes among patients undergoing in vitro fertilization; however, their involvement in repeated implantation failure has not been assessed. We explored possible associations of serum homocysteine and vitamin B12 with repeated implantation failure. Material and methods A retrospective analysis of 127 women who underwent ≥ 3 unsuccessful embryo transfers during 2005–2016, at the Fertility and In Vitro Fertilization Unit at Carmel Medical Center. After at least 3 IVF failures serum levels of homocysteine and vitamin B12 were measured. Results The mean patient age was 33.5 ± 5.2 years. The mean number of embryo transfers was 4.6 ± 1.5. The mean total cumulative number of embryos transferred was 10.4 ± 5.2. Mean serum levels of homocysteine were 8.6 ± 3.7 µM/L, and of vitamin B12 were 302.5 ± 155.3 pg/ml. Homocysteine levels were within the normal range (< 14 µM/L) in 95.8% of the patients. Yet, the levels of homocysteine correlated with both the number of failed embryo transfers ( r = 0.34, p = 0.004) and the total cumulative number of transferred embryos ( r = 0.36, p = 0.002 ). Conclusions Our findings suggest an association between serum homocysteine levels and the occurrence of repeated implantation failure, even when homocystein levels were within the normal range. It should be studied whether nutritional supplementation to modulate serum homocysteine levels may improve treatment outcome.