Homocysteine metabolism in the pre-ovulatory follicle during ovarian stimulation.

BACKGROUND: Ovarian stimulation gives rise to supraphysiological estradiol levels, which may affect oocyte quality. This study aims to investigate whether ovarian stimulation deranges the homocysteine pathway thereby affecting the pre-ovulatory follicle. METHODS: Blood samples were collected on cycle day 2 and the day of hCG administration in 181 women undergoing ovarian stimulation for IVF. In each subject, the diameter of the two leading follicles was measured and the corresponding follicular fluids were collected. In blood and follicular fluid samples, total homocysteine (tHcy), folate, cobalamin and pyridoxal'5-phosphate (PLP) were determined. According to the blood folate levels, women were classified as either folic acid supplemented (n = 113) or non-supplemented (n = 32). RESULTS: Ovarian stimulation resulted in a significant decrease in blood tHcy and cobalamin levels (both P