The role of the endometrial heavy metal (cadmium, lead, mercury and arsenic) concentrations in the etiology of unexplained infertility

Infertility is a common problem and affects approximately one in seven couples. 15-30% of couples who are unable to conceive are determined to have unexplained infertility because standard clinical investigation have not highlighted any abnormalities. Several research and studies on infertility showed that many molecular factors and mechanism have a role during sperm transportation, fertilization and embryo implantation. Evidence from animal and human studies demonstrated that heavy metals may have detrimental effect on these processes. The aim of this study was to determine the role of heavy metals on the etiology of unexplained infertility. For this purpose we compare endometrial heavy metal (cadmium, lead, mercury and arsenic) concentrations of patients with unexplained infertility and normal fertile (control) women.Nineteen (19) women with unexplained infertility and 18 normal fertile women were enrolled in this study. An endometrial biopsy was collected from women during the putative window of implantation (cycle days 20-24). Concentration of cadmium, lead, mercury and arsenic were measured in endometrial biopsy specimen using atomic absorption spectrometry.Out of 19 cases in study group, cadmium was detected in all cases with unexplained infertility (100%), whereas it was detected only 6/ 18 ( 33%) of fertile control women and the difference was found to be statistically significant (p=0.001). Cases with unexplained infertility have an increased risk ratio 3.0 for detection of cadmium in endometrial biopsy sample than fertile controls. Lead was detected 5 cases with unexplained infertility (26%) and 1 case in the control group (p=0.18). Mercury and arsenic were not detected in any of the endometrial samples of unexplained infertile cases and fertile controls women. Infertile women have a higher concentration cadmium in endometrial biopsy sample than fertile control women (32.09 µg/l (range: 16.92-61.52) versus 3.51 µg/l (range: 0.00-16.39), respectively; p=0.0001) There were no statistically significant diferences between cases and controls in the concentrations of lead (0.057 µg/l (range: 0.00-0.32) versus 0.0017 µg/l (range: 0.00-0.03), respectively; p=0.07).In conclusion, a significant difference in endometrial cadmium levels between unexplained infertility and fertile women suggests that cadmium may be involved in etiology of unexplained infertility.