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Puberty 101: Girls

As a mother of twin teens, I’ve seen it happen. Suddenly, the little girl you’ve raised and loved looks different. Changes in her body have her asking questions, or she may be seeing her friends changing and wonder when it will be her turn.

Of course, as parents, we all went through puberty ourselves — though it feels like ages ago! For kids starting puberty, understanding the changes they will experience before they happen can be reassuring.

READ MORE: Puberty 101: Boys

What is puberty?

Biologically speaking, puberty is the time when kids’ bodies mature sexually, making them capable of reproduction. Practically, it’s a series of changes that can be exciting, confusing, awkward and wonderful. For girls, puberty generally begins between the ages of 9 and 12. Because there’s such a wide age range, it’s common for two girls of the same age to look really different – one still like a little kid, and the other more like a young adult.

Breast development

One of the first signs of puberty in girls is the development of breast buds. Breasts begin as swelling under the nipples, and feel hard —  sometimes girls might even be worried there is something wrong. Breast buds can feel sore or tender at first. Wearing loose clothing and getting a training bra can help.

Breasts will continue to develop during the years of puberty, sometimes at uneven rates. Don’t worry, they will even out.


A girl’s first menstrual period generally occurs about two years after breasts start developing. Most girls will get their period at around the same age as their mom and sisters. Some girls eagerly await their first period, while others aren’t so sure. Helping kids understand that it’s a normal and healthy part of growing up can ease anxiety.

  • Prepare your daughter with an explanation of how menstruation works. Ask your pediatrician to recommend a good book or pamphlet to help explain.

  • Prior to starting menstruation, many girls will experience vaginal discharge that is clear, milky or white. This is normal and means their bodies are starting to change.

  • Show your daughter how to use sanitary pads and make sure she has a few in her backpack and at home for when her period starts. Some girls may be comfortable trying tampons soon after they start their periods.

  • Reassure your daughter that she can still be active, swim and do sports when she has her period. Exercise can even help alleviate some menstrual symptoms like cramps.

Growth spurt

The adolescent body grows at a rate faster than any other time in life, except for infancy. Kids can grow up to four (or more) inches a year, and the growth spurt generally lasts two to three years. That’s a lot of new pants, shoes and shirts! At the end of the growth spurt, kids will have nearly reached their adult height.

  • Quick growth can sometimes be hard for kids themselves to keep up with — episodes of clumsiness and feeling awkward are normal.

  • Girls’ hips widen and they will start to gain and redistribute weight throughout their bodies. This is normal, and it’s important for girls to keep eating healthy foods and getting enough calories to nourish their growing bodies.

Mood and other changes

The hormones that bring on puberty can also affect kids’ moods. It’s normal for kids to sometimes feel confused or have strong emotions. They might feel especially sensitive or lose their tempers more than normal.

Other changes associated with puberty include:

  • Increased body odor. Girls should shower or bathe daily. Using deodorant can help too.

  • Acne. Pimples are, unfortunately, a normal part of puberty. Wash the face twice a day with mild soap. A pediatrician can also offer tips for dealing with acne.

  • Pubic hair. For girls, this is another early sign of puberty. Hair in the underarm area generally appears later during the puberty cycle.

All these changes can feel overwhelming, but keep in mind that puberty is also a time when girls can nurture deep friendships, become passionate about causes, interests and hobbies, and develop a new sense of independence. It’s an adventure!

In rare cases, kids who start developing very early or very late may have a medical problem that needs to be treated. If you are concerned about your daughter’s development, talk to your doctor. You can also call our Teen Health Clinic, which has specially trained staff who help teens and young adults manage all the health problems they may face — from routine to serious. Above all, keep the conversation about puberty open and honest, both with your providers and with your kids.