in their most sexually active stages of life
"Usually a sexually transmitted disease, it occurs mainly in sexually active women under age 25, more often in those using intrauterine devices (IUDs)."
Mainly in their20 s and30 s, they are in a sexually active age group.
The number of reported cases of STD from those at the age of 20-39 years who were sexually active was the largest, accounting for 70.65% of the total cases.
To be sexually active. Used of a woman.
a man who is virile and sexually active.