Oligospermia, also called oligozoospermia, means a lower-than-expected sperm concentration in semen.

Common contributing factors include varicocele, hormonal or testicular disorders, genital-tract obstruction or infection, heat exposure, smoking, heavy alcohol/drug use, obesity, some medicines including testosterone/anabolic steroids, prior chemotherapy/radiation, and genetic causes. A semen test can vary, so clinicians generally confirm an abnormal result with repeat semen analyses and assess for reversible causes.

If this is from a report, share the sperm concentration, total count, progressive motility, morphology, abstinence duration, and test date and I can help interpret it. A reproductive urologist/andrologist is appropriate, especially if results are markedly low or conception has not occurred after 12 months of regular unprotected intercourse.