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When does puberty happen and what changes?


Most girls start to go through puberty sometime between the ages of 9 and 13. Puberty is the process that changes the body from that of a child to that of an adult.

On the outside of the body, “breast budding” is usually the first sign that girls have entered puberty. It can be scary and exciting all at the same time. Girls notice slight changes in the size and shape of their breasts as they begin to grow. Girls might also notice acne, body odor, sweat and hair growing in the armpits and around the vulva. Hair on the legs will become more evident. Girls may also grow wider hips and larger breasts, although the size and shape of both of these body parts will be different on different girls. All of these changes are the result of hormones—chemicals in the body.

Mood swings can also be a part of puberty. A girl might feel happy one second, sad and angry the next—without being sure why she’s feeling that way. This can seem like a roller coaster ride because a girl feels like she has no control. The good news is that these mood swings are part of the process, and both boys and girls go through them. If you know what to expect, sometimes it’s easier to deal with them when they happen.

Inside a girl’s body, her uterus, cervix and ovaries are growing and maturing too. Sometime in the middle of puberty, girls usually get their first menstrual period.


When a guy starts going through puberty, the first thing that happens is growth of the testicles. In general, all of the other changes happen as a result of the increased testosterone, a hormone produced by the testicles.

The first thing a guy usually notices is hair growing under his arms, around his penis area (genitals) and on his face. Hair on other parts of his body will often get thicker and darker too. Some guys have more hair than others. Genetics play a part in this. That means if your biological dad, for example, has a lot of body hair, you might have a lot of body hair, too. Guys may also notice acne, body odor or increased sweating. Like girls, guys will notice changes in mood. This is due to the changing hormone levels that take place during puberty.

Also during puberty, a guy’s voice box grows. That’s what causes his voice to crack and squeak. It takes a little time for the cracking to stop, as the voice deepens and settles into its adult tone. The penis, testicles and scrotum also grow during puberty. The testicles will also start to produce sperm. Since your testicles are growing faster than your penis at first, it might seem like your penis is shrinking. It’s not.

During puberty, it’s also common for boys to have large growth spurts, times when they grow fast over a short period of time. This rapid growth can cause “growing pains,” when joints and muscles ache and get sore. When a guy grows very fast, he doesn’t have time to get used to his larger limbs, so he sometimes feels awkward and clumsy.

Another thing that can happen to guys during puberty is getting an erection out of nowhere. It is perfectly normal for teen guys to get erections when they don’t even feel turned on. They can happen without warning and at embarrassing times. Most teen guys who are going through puberty get spontaneous erections. They happen a lot less once a guy finishes puberty, although adult men still get spontaneous erections every once in a while.

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