Every year since your child was 2 or 3 years old, she/he has gained about 5 pounds and grown about 2 inches, on average. During puberty, you can expect that rate to double.

The American Academy of Pediatrics (AAP) says puberty is made up of a clear sequence of stages, affecting nearly all bodily systems. A girl's ovaries start producing estrogen (the female sex hormone), and a boy's testicles start producing testosterone (the male sex hormone).

The timing of a child's physical development can vary a lot, but puberty often begins earlier than parents think. Boys start puberty a little later than girls, typically between ages 9-13, where it’s between ages 7-11 for girls.

Physical changes during puberty tend to be gradual and steady. What changes can parents expect when their child hits puberty? How can you tell what’s normal and what’s not?

Girls: The AAP offers what to expect for girls:

  • Breast changes – The first visible sign of puberty in girls is often breast budding, a nickel-sized lump under one or both nipples, usually at age 9 or 10. Some girls show breast buds as early as age 8, and others not until 13. Don’t be concerned if one breast develops before the other, as this can happen at the onset of puberty. Breast buds can feel tender and sore, and are firm to the touch.
  • Hair growth – The second sign of puberty is often the appearance of pubic hair. About 10-15 percent of girls will develop pubic hair before the breasts begin to bud. The hair is sparse, straight and soft at first and then becomes darker, curlier and coarser as it fills in. About two years after the onset of puberty, hair begins to grow under the arms as well.
  • Body shape – Another sign of puberty in girls is changing body shape, particularly extra fat in the belly area (some call it “baby fat”). Weight gain can cause anxiety for girls. This is part of normal development, and her body will redistribute the fat from the stomach and waist to the breast and hips.
  • Period – Although there’s no way to pinpoint when your daughter will get her first menstrual period, it is often at about the same age as their mothers did, and it typically happens about 1.5- 3 years after breasts start to develop. Several months before her first period, she may notice clear or white discharge, which is normal. The first several periods are almost always painless, but eventually she may experience cramps and other symptoms. Menstruation may be irregular at first, with as many as 6 months passing between periods.
  • Height – The growth spurt starts shortly after breasts begin to develop. On average, rapid growth occurs around age 11.5, but it can begin as early as age 8 or as late as 14.

Boys: The AAP offers what to expect for boys:

  • Penis and testes – The first sign of puberty in boys is often enlargement of the testes and the scrotal sac (a near doubling in the size). As the testicles grow, skin of the scrotum darkens, enlarges, thins, hangs down from the body, and becomes dotted with tiny hair follicles. These changes may occur between ages 9-14, with an average age of 11. In most boys, one testicle (usually the left) hangs lower than the other. The penis also grows in length, then in width. About 1 in 3 boys have harmless, barely noticeable pimple-like lesions around the crown of the penis.
  • Hair growth – The next sign of puberty is pubic hair. It starts with a few light-colored downy hairs appear at the base of the penis, and soon turns darker, curlier and coarser in texture. About two years after the appearance of pubic hair, sparse hair begins on a boy’s face, legs, arms, and underarms and, later, the chest.
  • Wet dreams – About one year after the testicles begin to enlarge, boys often experience their first ejaculation. The testicles now produce sperm in addition to testosterone. A teen’s first ejaculation may occur at night while he’s asleep. A nocturnal emission, or wet dream, is not necessarily the result of a sexual dream. He can’t prevent it, and it will stop as he gets older.
  • Erections – Erections are unpredictable during puberty, and may pop up for no reason (and without having sexual thoughts). There isn’t much boys can do to stop spontaneous erections, but over time they will become less frequent.
  • Voice changes – Your son’s voice may crack as he speaks. This means his voice box and vocal cords are growing, and his voice is deepening. It’s a normal part of the growth process, and once the larynx reaches adult size, the cracking will stop.
  • Breast swelling – Early in puberty, most boys experience nipple soreness or tenderness. About 3 in 4 boys experience some swelling of the breasts, which usually resolves in a year or so.
  • Weight/height – During early puberty, boys may have a chubby appearance, but it is often offset by a dramatic increase in height during his growth spurt. Boys usually trail behind girls in height by about two years, but continue to fill out with muscle mass long after girls do.

Some children start puberty very early or very late. The AAP says two boys or girls exactly the same age can start or end puberty years apart, yet still fall within what is considered "normal" growth. Let your doctor know if your child’s development does not follow the typical pattern to rule out any medical problems.

For instance, check with your doctor if your daughter begins pubertal changes before age 8 or if there are no changes by age 13. Likewise, let your doctor know if your son enters puberty before age 9, or if there are no pubertal changes by age 14.

Also, talk to your doctor if your daughter has not menstruated by age 16 or 17, or if she experiences abdominal pain or a sudden change in her periods.

How can you support your child during puberty?

It’s always a good idea to talk to your child in advance so she/he knows what to expect during puberty. Talk to your son about how voice cracking and spontaneous erections, while embarrassing, happen to all boys during puberty and are nothing to be ashamed of. Help your daughter prepare for her first period early on. Talk about how it’s a normal bodily process, and have her keep a few sanitary pads in her backpack so she’s prepared.

Your child may be more sensitive about how she/he looks and embarrassed about the physical changes taking place. Many boys worry about their penis size, and spend time inspecting their penis and comparing themselves to other boys. Your son may need reassurance from his doctor that all is okay. Girls are often self-conscious about their changing bodies, so it’s important to promote a healthy body image in your daughter.