
No. Contrary to popular belief it doesn't just affect older people. In reality it can and does affect fit, young, active females of all ages: from teenagers who have 'giggle incontinence'; women who have just had babies; and in older women it tends to be urgency/frequency & stress incontinence.
One of the main triggers for women is childbirth (over 30% have it 3 months after giving birth and 40% have it six years after having a child) so this is an issue which affects women in their 20s, 30s and 40s.