“Tight underwear lowers sperm count.”
Some observational studies find higher counts in men wearing boxers, but findings are inconsistent and confounded. A causal effect or improved pregnancy rate from changing underwear is not established.
Tight underwear has not been proven to cause low sperm count. A fertility-clinic study linked boxer use with higher average counts, but it did not randomly assign underwear or test whether switching improved fertility.
Men attending a fertility clinic may differ from the general population. Clothing, habits and other unmeasured factors can travel together.
Safety note: Do not assume an underwear choice explains an abnormal semen test.
Talk to a healthcare professional if: Have persistent fertility concerns assessed rather than relying on a clothing change.
Comfortable, looser underwear is a reasonable preference, not a medically required fertility fix.
Choose what is comfortable without treating underwear as a substitute for evaluation.
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