The Association of Gut Microbiota and Spermatogenic Dysfunction

Inclusion Criteria: * Aged 18 to 45 years, males * Body Mass Index (BMI):18.5-29.9 kg/m\^2 * After an abstinence period of 2-7 days, two abnormal semen analysis, the absence of spermatozoa from both replicates will be included in the azoospermia group, the total sperm number (\<39\*10\^6 per ejaculate) or the sperm concentration ( \< 15 \* 10\^6 per ml) will be oligozoospermia group, the progressive motility (PR) (\< 32%) will be asthenozoospermia group; the percentage of morphologically normal spermatozoa (\<4%) will be teratozoospermia group * Willing to provide feces, urine, blood samples, able to complete study questionnaires aimed at lifestyle factors (cigarette smoking, high temperature environment and others ) and other data collection instruments (e.g. physical activity, food frequency questionnaire, stress and others) Exclusion Criteria: * Age \< 18 or \> 45 years * History of Zocanidin, Vitamin E, antibiotics, clyster, gastrointestinal endoscope in the past 30 days, or other drugs known to interact with semen quality or gut microbiota, history of high alcohol consumption (liquor over 200 ml, beer over 1000 ml) in the past 7 days or drinking every week in the past month * A known genetic cause of male factor spermatogenesis dysfunction, including chromosomal or gene disorders (e.g. Y chromosome deletions, CFTR mutation) * History of male reproductive system (e.g. testis, epididymis, seminiferous duct and others) damage, surgery, tumor or infection * History of Crohn's disease, ulcerative colitis, acute gastrointestinal disease, renal failure, liver cirrhosis, hypoplasia, X-rays exposure and other diseases related to spermatogenic dysfunction, history of intestinal gastrointestinal surgery (exclude appendix surgery) * History of psychoses or other mental conditions that would result in cognitive impairment and inability to participate in any part of this study including the informed consent process