Explaining menstruation to your daughter

Explaining menstruation to your daughter

Talking to your daughter about her menstrual period is a great way for her to feel comfortable with the changes that occur both physically and emotionally during this time in her life.

Prepare by brushing up on your female anatomy. That way, she’ll see you as a trusted source of information, help and support. Here are some menstruation biology basics.

Unique menstruation timing

Most girls get their first period between 11 and 13 years old, though it can start anywhere from ages 8 to 16. Generally, a woman has about 480 periods (fewer if she has pregnancies) throughout her adolescence and adulthood until she reaches menopause (often around age 51), at which point her periods stop.

This may come as a surprise, but your daughter’s monthly cycle doesn’t necessarily take place once a month. The average cycle time for most girls is 28 days, but her cycle may last from 21 to 35 days and still be normal. In her cycle, day one is the first day of her period, or the first day she begins to bleed.

If she has a short cycle, it’s likely that she will have a menstrual period more often than once a month. However, if her cycle lasts longer, she’s one of the girls who will have fewer periods in a year.

Reproductive organs explained

As you explain your daughter’s menstrual period, it's helpful to remind yourself what parts make up a woman's reproductive organs.

The woman’s reproductive system includes:

  • Two ovaries: this is where eggs (ova) are stored and released. A human egg is tiny (120 micrometers). This is about the width of a human hair.
  • The womb (uterus): where a fertilized egg implants and a pregnancy grows.
  • Two fallopian tubes: these are two thin tubes that connect the ovaries to the womb.
  • The cervix: the lower part of the womb that connects to the vagina.
  • The vagina: A tube of muscle connecting the cervix to the outside of the body. (Your vagina is actually inside your body – the part on the outside that you can see and which is frequently mistakenly called the vagina, is your vulva.)

The role of hormones

Each month, a woman’s reproductive system repeats a regular pattern of events that are controlled by hormones

Hormones are substances produced by her body that control her body’s functions. As your daughter approaches puberty, a part of her brain called the pituitary gland begins releasing more and more of some specific hormones.

These hormones stimulate her ovaries to produce oestrogen and another part of her body to produce other hormones called androgens. These hormones cause many of the physical changes that take place during puberty and over the phases of her monthly menstruation cycle.

Phases of the menstruation cycle

  1. Pre-ovulation (called the follicular phase)
    Women and girls have two ovaries that contain thousands of eggs (ova). During this phase, hormones stimulate the development of eggs; at the same time, the soft lining (called the endometrium) of the uterus (the place where a baby can grow) starts to thicken.
  2. Ovulation
    This occurs when a mature egg (occasionally two) is released from the ovary. After the egg is released, it travels along the fallopian tube to the thickening lining. If sperm from a male fertilizes the egg, the egg will move into your uterus and develop into a fetus. Ovulation usually happens around 10 to 16 days before the next period.
  3. Premenstrual (called the luteal phase)
    After ovulation, hormones trigger the body to continue developing the lining of the uterus, in preparation for a fertilized egg. During this phase, if your daughter were to become pregnant, the egg moves into the uterus and then attaches to the lining. If she is not pregnant, the lining of the uterus is shed through the vaginal opening during menstruation.
  4. Menstruation
    The womb lining leaves your body through the vagina as a reddish fluid containing blood – typically about a quarter of a cup of blood (though it can seem like a lot more). This is youd daughter’s “period” – it is also called menses – and it will last between three to seven days. The first day of bleeding is officially day one of her menstrual period.


  • The American Congress of Obstetricians and Gynecologists (ACOG), Patient brochure 49

  • ACOG, Patient brochure: midlife transition and menopause

  • ACOG, Medical Student Education Module 2008

  • Comprehensive Gynecology Review, 3rd edition; edited by F. W. Ling, L. A. Vontver, and R. P. Smith

  • Bloom and Fawcett: A Textbook of Histology, 11th edition, by Don W. Fawcett

  • Emans, Laufer, Goldstein's Pediatric and Adolescent Gynecology, 4th edition, by S. Jean Emans and Marc R. Laufer)