Guide to the Teen Menstrual Cycle
UPDATED: JULY 2025
I vividly remember my first period - I was in grade 6 and wearing beige pants. I also didn't tell my mom for two whole days. I relied on the teachings of Fully Alive (I was a Catholic school kid) and Are You There God? It's Me Margaret as reference material for the big day. Nevertheless, I still found myself wholly unprepared.
Chances are you're reading this article on your daughter's behalf. If so, I believe it's really important to have open communication about menstruation - otherwise you may not hear about this huge life event until a few days later (sorry mom!). The Ontario curriculum discusses puberty and menstruation in grade 5 - usually when a girl is 10-11 years old. Most girls however, begin their menstrual cycle when they're 12 years old (although some may experience as young as 8!). That said, girls may not remember the ins or outs of menstruation, or their teacher may not have have spent too much time on the subject.
What your daughter should know
She may not experience normal periods...
...For the first year. When menstruation begins, it's common for a girl's period to be irregular in the first year, and can take between 2-3 years for her to achieve cycle regularity.
Irregular periods in a teen are defined in a few different ways:
Between 1-3 years after the start of her period, her cycle is considered irregular if it occurs less than 21 days or more than 45 days
3 years after the start of her period, her cycle is considered irregular if it occurs less than 21 days or more than 35 days, or if she experiences less than 8 cycles per year
After the first year of her period, her menstrual cycle is more than 90 days long
If your teen is experiencing irregular periods after the first year of having a period, this may be a sign of PCOS. The other criteria that teens need to meet is high androgen hormones seen biochemically (testing for testosterone via blood work) or clinical hyperandrogenism where acne and male-pattern hair growth is assessed. Ultrasound is not required in an adolescent PCOS diagnosis in the first 8 years of having a period.
Painful periods are NOT normal
Every woman may feel slight cramping at the start of her menstrual cycle. That said, extreme, constant pain is not normal and could be a sign of a health issue like PCOS or even endometriosis. The oral contraceptive pill may be offered to teens manage the pain, and support their quality of life.
Sharing your experience with your daughter
You may not want to wait for your daughter to take the first step and ask you about your first experience - after all (like I was) she may be incredibly embarrassed. It may be a good idea for you to broach the issue and see if she's ready to have the discussion. After all, more communication is better than no communication. Learning about your experience, may also help her become more comfortable in her body.
Things you may want to share:
The age when you first got your period.
How was your first period? Has it stayed the same? Has it changed?
Have you ever had extremely painful periods?
Did you use anything to track your period? Or do you currently have a favourite app to track your period?
How long are your cycles?
Do you experience any clotting? Stringiness? What does the colour usually look like?
Do you notice a change in cervical fluid?
Is there a history of PCOS or endometriosis in your family?
Do you ever get any PMS symptoms?
What are her menstrual hygiene options?
Final Notes
Empowering your daughter with this information is incredibly important. She has the right to know what's going on with her body during this transformative time. If you're not comfortable sharing your experience, or you don't think your experience is normal, you may want to visit a Naturopathic Doctor.