When I am teaching one of the biggest questions young girls have is "When will I get my period?", or "How will I know?" It would be wonderful if we knew and could share with our daughters when they were going to get their first period. It is exciting and a life-changing event when it finally happens. Predicting when a girl will get her period is not an exact science and is different for everyone. But, there are some helpful signs that you can look out for and discuss with your daughter so that she is prepared for when she does begin menstruating.
Signs that your daughter is about to start her period:
Menarche, or the onset of menstruation (Menses = Month in Latin) can begin as early as nine or ten years old and some girls may get their periods as late as 14, 15 and even 16. The average for a girl to get her first period is 12 to 13 years old. Every girl is different, though. Some girls will start their periods earlier than other girls and some may start it later. Generally, I tell young girls that they will get their first period about the same time that their biological mother did. So, if you had your first period at 11 or 12, then you can expect your daughter will be starting her period around this same time. But this isn't always a great predictor since the age of menarche has been happening earlier in the last two generations. There are many theories why this is happening, nutrition, hormones, environmental factors or genetic variations - but we do not have conclusive evidence for the exact cause.
There are three changes that do happen before your daughter has her period. Once these changes have happened, you will have the signs that your daughter is about to start her period.
Breasts: Your daughter will have been developing breasts for about two years. Breasts will not be fully developed, and will have been growing on the chest for about two years. The breast size does not matter - remember every girls is different.
Pubic or underarm hair: She may have had some pubic and/or underarm hair for at least the last six months. There does not have to be full pubic hair, only that she will have started to grow some hair in the pubic area and/or under the arms.
Vaginal discharge: Your daughter will have been having some vaginal discharge for the last three months. Some girls can have this for 2-3 years before their period. If they have had discharge for longer, you may notice that it will get heavier and more frequent and this may be the sign that 3-6-12 months. I know, I know....this does not sound very accurate, but we can reduce it to within 12 months (usually). Vaginal discharge is totally normal! It is the vagina cleaning itself out and you can suggest your daughter wears panty liners if they are self-conscious or the discharge is a bit heavier.
QUIZ: Take these quizzes to find out when she (you) will start my first period?
Check out these links to find out if your daughter is displaying the common signs of starting her period.
Patient Info (UK Health Source)
Stages of Puberty in Girls (aka Tanner Stages)
The Tanner Stages of Puberty can offer a guide for growth during puberty. These are often referenced to find out when girls may start getting their periods. Of course, nothing is 100% but these are helpful guidelines.
Stage 1: After the 8th birthday
no noticeable physical changes
Stage 2: From age 9-11
First signs of breasts, called "buds' start to form under the nipple. May be itchy or tender, or one bud may be larger than the other, which is normal.
Darker area around the nipple (areola) will also expand
Uterus begins to get larger, and small amounts of pubic hair start growing on the vulva
Stage 3: After age 12
Acne first appears, armpit hair forms, height increases at its fastest rate
Stage 4: Around age 13
First period may arrive
Stage 5: Around age 15
Breasts reach approximate adult size and shape, though breasts can change through age 18.
Periods become regular after 6 months to 2 years
Females reach adult height 1 to 2 years after their first period
Pubic hair fills out to reach the inner thighs
Reproductive organs and genitals are fully developed
Hips, thighs, and buttocks fill out in shape