What it measures
The share of sperm with a normal shape of head, midpiece and tail, judged under a microscope against strict criteria. Under these criteria only a small share of sperm look normal, even in fertile men.
Why people test it
- Checked by couples who have been trying for a baby for a while.
- Part of a semen analysis, read alongside count, movement and volume.
Typical range
Reported as a percentage of the sperm counted. Labs usually compare it with World Health Organization reference values; ranges vary by lab, and the report shows the lab's own.
Finger-prick or vein?
A semen sample rather than blood, produced at home into the pot from the kit and posted to the lab.
Labs ask for a set number of days without ejaculation before the sample, as this affects the result; the kit instructions give the window.