noun
sperm motility (ratio)
Medical/biological term for the proportion of motile sperm in a sample.
精子運動率が低いと、自然妊娠が難しい場合がある。
When sperm motility is low, natural conception can be difficult.
Compound of 精子 (sperm) + 運動 (movement/motility) + 率 (rate/ratio).