The research objective was to evaluate the blood vitamin B12 levels in females before and after two months of vitamin B12 supplementation. Additionally, the study intended to investigate the effects of this supplementation on antral follicle count (AFC), the number of dominant follicles (DF), the outcome of intrauterine insemination (IUI), and the effect of the outcome by age, and BMI, cause of infertility and types of infertility . A randomized controlled trial was undertaken, including 100 couples that have provided comprehensive data. Segregated into two equivalent groups based on their vitamin B12 intake. Groups A and B, group. Group A comprises 50 pairs of individuals using B12 supplements for eight weeks, and Group B contains no additional elements. Collect blood and seminal plasma samples from all couples to assess their vitamin B12 levels. The two groups underwent ovulation induction and intrauterine insemination (IUI) concurrently with the medical evaluation. Group A started after two months of supplement, but Group B began immediately. Vitamin B12 increases female blood levels, antral follicle count, and dominant follicles (DF). The pregnancy rate has little effect. The antral follicle count and numbers of dominant follicles did not differ between pregnant and non-pregnant women after vitamin B12 supplementation.