Hormonal Changes in Teen Girls

A girl's body seems to change in the blink of an eye, once the hormonal effects of puberty begin. Girls typically start the transition into womanhood between the ages of 10 and 14, although the process can begin sooner or later than that. Pubescent girls are prone to making a mountain of a molehill when it comes to how they view real or perceived physical imperfections, points out the American Academy of Pediatrics. A slightly bent nose or a couple of pimples can make an adolescent girl extremely self-conscious about her appearance.

How It Works

Puberty begins when a girl's body emits a hormone called "gonadotropin-releasing hormone," or GnRH. When GnRH finds its way to the pituitary gland (a pea-sized gland tucked under the brain), it releases two additional puberty hormones -- "luteinizing," or LH, and "follicle-stimulating hormone," or FSH -- into the bloodstream 6. LH and FSH signal the ovaries to produce yet another hormone called "estrogen." Working as a team, these hormones prepares a girl’s body for pregnancy. Teen girls who are thinking about becoming sexually activity should talk to their doctor about birth control options and protection from sexually transmitted diseases.

What to Expect

Breast development, which begins with an ever-so-slight amount of swelling under the nipples, is often the first hint that the hormonal changes of puberty are under way, explains the National Institutes of Health's MedlinePlus 1. Hair growth under the arms, in the pubic area and eventually on the legs are also common signs of puberty in girls 6. Acne may begin to show up in a formerly flawless face around age 13. Increased fat around the hips makes a girl's body appear more "womanly," but it also tends to cause unwelcome weight gain.


Most adolescent girls start menstruating two years or so after breast development begins, explains KidsHealth.org. Girls are equipped with two ovaries, and each one contains thousands of eggs. During the menstrual cycle, an egg is released from an ovary. It travels through the fallopian tube, a tiny tube that connect a female's ovaries to her womb or uterus, where it settles. If the egg isn't fertilized by sperm, the uterus releases blood and tissue, which results in menstruation. Some girls may become moody, emotional or irritable in the days leading up to their period. This is known as "premenstrual syndrome." PMS fades away once a girl’s period starts.

Premature and Late Puberty

Some girls can show signs of puberty as young as age 6 or 7, explains the AAP 6. Premature or precocious puberty is rare. It can be a sign of a medical problem, such as issues with the thyroid gland or the ovaries. Delayed puberty, defined as showing no hint of breast development by age 14, is sometimes caused by malnutrition, explains the American Academy of Family Physicians. Both premature and delayed puberty can also be hereditary 6. Talk to you daughter's doctor to rule out any potential health problems associated with an untimely onset of puberty.

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