RESUMEN
OBJECTIVE: To determine the role of endometrial concentrations of heavy metals (cadmium, lead, mercury and arsenic) in the aetiology of unexplained infertility. STUDY DESIGN: Thirty-three women with unexplained infertility and 32 fertile women were recruited. Endometrial biopsies were collected during the putative window of implantation (cycle days 20-24). The concentrations of cadmium, lead, mercury and arsenic were measured in endometrial biopsy specimens using atomic absorption spectrometry. RESULTS: Cadmium was detected in 91% (30/33) of women with unexplained infertility, compared with 34% (11/32) of fertile women. The median endometrial cadmium concentration was 19.58 (interquartile range 1.46-30.23)µg/l in women with unexplained infertility, compared with 0.00 (interquartile range 0.00-0.40)µg/l in fertile women. Lead was detected in 15% (5/33) of women with unexplained infertility and 3% (1/32) of fertile women. Mercury and arsenic were not detected in any endometrial samples from either group. CONCLUSION: A significant difference in endometrial cadmium concentration was found between women with unexplained infertility and fertile women. This suggests that cadmium may be a contributing factor in the aetiology of unexplained infertility.