Everyone's different

Remind your child not to worry about when friends begin to menstruate — or if their periods seem different. Explain that menstruation, including cycle length and flow, varies from person to person and sometimes month to month.

It's also common for teens to have irregular periods. It might take six years or more after your period starts for your cycle to become regular. The average menstrual cycle lasts 28 days — counting from the first day of one period to the first day of the next period. Although cycles in young teens can range from 21 to 45 days, longer cycles are more common for the first few years after menstruation begins.

Teach your child how to track periods on a calendar or by using a smartphone app. Eventually your child might be able to predict when periods will begin. Keeping track of periods can also help your child and your child's doctor identify any possible menstrual disorders or other health problems.

Schedule a medical checkup if your child:

• Hasn't started menstruating by age 15 or within three years of the start of breast growth — or breasts haven't started to grow by age 13
• Goes three months without a period after beginning menstruation or suspects pregnancy
• Has periods that occur more frequently than every 21 days or less frequently than every 45 days
• Has periods that become irregular after having been regular
• Has periods that last more than seven days
• Has severe pain during periods
• Is bleeding between periods
• Is bleeding more heavily than usual or using more than one pad or tampon every one to two hours
• Suddenly gets a fever and feels sick after using a tampon