If a female misses their period for three or more months in a row, it's called amenorrhea. This can happen for many reasons, such as hormonal changes (especially in the first few years after periods start), heavy exercise, stress, reactions to medicines, being underweight or overweight, pregnancy, taking certain medicines, or other medical conditions.

Treatment for missing periods depends on the cause. Often, periods will become regular on their own.

Help your child track periods. Use a calendar or your phone to record:

• Start-and-end dates
• How heavy the flow is (light, medium, or heavy, and whether there are clots)
• Any cramps, headaches, or bloating

Depending on the cause of your child's amenorrhea, your healthcare provider may recommend that your child:

• Wait to see if periods come back on their own.
• Manage stress by getting enough sleep, exercising, and trying relaxation techniques, such as yoga or listening to music.
• Take hormonal birth control (such as a birth control pill) to balance hormones.
• Stop any medicines that may interfere with periods.
• Follow an eating and exercise plan to reach a healthy weight.
• See a gynecologist (a doctor who specializes in female health) or other specialist for additional testing.
• Follow up in a few months to see if their periods have become more regular.

Important: People with amenorrhea can still get pregnant if they have sex. Talk to your child about using condoms to protect against pregnancy and sexually transmitted diseases (STDs, also called sexually transmitted infections or STIs).

Your child:

• Doesn't get their period within 2–3 months
• Starts having periods every 4–5 weeks, then stops getting their period again
• Gets new symptoms such as headaches, extreme thirst, changes in vision, vaginal dryness, acne, milk coming from the breasts, or extra hair growth on their body

How can hormonal birth control make periods more regular? Hormonal birth control works by balancing hormones, which helps periods come regularly. It comes as a pill, a shot, an implant that goes just under the skin, or an IUD (intrauterine device), which is put into the uterus. It can take some time for the hormones to get to the right level and the body to adjust to the hormones, so at first, it may cause periods to come irregularly. Over time, periods usually become more regular when hormonal birth control is used.