<human>:  How old are women when they have their first period?
<bot>: First periods happen around age 12 for most girls, so their first period will be at age 12 on average. Note that girls who are overweight or obese may have their first period earlier than average. However, girls may have their first period around age 8 or 9, and can even have it as young as age 4 or 5. It's normal for some girls to not have their first period until age 14.