Young girls’ change starts with menarche

Dr. Tristi Muir

Dr. Tristi Muir

Our Bodies, Our Lives

Menarche is the time when a girl has her first period. The normal age range of menarche is 9-15.

As the average weight of people — including children — in our country has increased during the past four decades, the age of the onset of puberty and menarche has decreased.

Periods are usually light and irregular in the beginning. Within two years of menarche, two out of three girls will progress to regular, predictable periods occurring about monthly — anywhere between 21 and 45 days — and lasting from three to seven days.

Menarche is a sign that the orchestration between the brain (the conductor) and the ovarian hormones (the orchestra) has resulted in stimulation and shedding of the uterine lining.

The uterus contracts to shed the uterine lining, which is the source of pelvic cramping and back pain. Through the course of a period, vaginal bleeding may change in intensity and color.

Along with hormonal effects on the uterus, girls also may notice water weight gain, bloating, breast tenderness and of course moodiness before the start of her period, called PMS or premenstrual dysphoric disorder (PMDD).

While many people think that puberty is all about starting a period, there are other important changes that are taking place throughout the body. Periods do not usually begin until after a growth spurt, breast development and pubic hair has started to grow.

As the brain starts increasing hormone production to wake up the ovaries, hormones also stimulate a rapid growth in height. This growth spurt, of up to 4 inches per year, usually occurs between the ages of 9 and 11.

During this time of rapid growth, you might want to episodically shop for school clothes rather than buying them all before the start of school. Most girls reach their adult height by the age of 18.

The largest organ in our body, the skin, undergoes a tremendous amount of change with puberty. Two million to four million sweat glands become more active — particularly in the underarms — and the oil glands in the skin — particularly the face, chest and upper back — become overactive.

Pimples are the norm. With all the changes occurring in the skin, it’s important to keep it clean and avoid popping pimples. If acne gets out of hand, see your doctor. There are many medications that can keep the acne at bay and help avoid acne scarring. Fortunately, the oil glands usually calm down by the end of puberty and acne improves.

The skin in your mouth can change as well. The gums become more sensitive and can swell and bleed more readily. Routine care, brushing and flossing your teeth and gums becomes more important to prevent gum disease and bad breath.

The fat in a girl’s body is routed to other areas when the hormones of puberty are turned on. When the ovaries are stimulated to produce hormones, estrogen is a principal product of this production.

Estrogen stimulates breast development even before the orchestration of the ovary is in sync enough to have a period. It is not only the breasts that gain fat, but the hips attract fat to add curves to a girlish figure.

Every woman has their own story of when their period started and how puberty affected her body and self-perception.

I encourage each mother to be the person your daughter can come to with questions. Educate yourself about what to expect and provide good information to empower your daughter to meet these changes head on.

Our Bodies, Our Lives focuses on issues surrounding women’s sexual, gynecological and emotional health. Dr. Tristi Muir is the director of the UTMB Pelvic Health and Continence Center at Victory Lakes. Visit

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