Now that we’ve discussed the female sexual and reproductive system, let’s explore female maturation. The female reproductive system undergoes cyclic hormonal events that lead to pubertal changes, menstruation, and eventually, menopause.
Female Puberty
After birth, the female’s sexual development progresses slowly until puberty. The first stirrings of puberty, usually begin at about age 8, but can begin as late as 14 or 15. Puberty lasts from 3 to 5 years on average.
No one really knows how the body knows its own age or that it is time for puberty to begin. Newer research suggests that the onset of puberty may be related to weight— girls who are overweight begin menstruating earlier than those who are average or underweight (Biro et al., 2003). The onset of puberty can also vary with race. For example, African American girls reach puberty earlier than Caucasian girls (Kaplowitz et al., 2001). African American girls begin puberty between 8 and 9 years of age, a good 1 to 1-У2 years earlier than Caucasian girls (Herman-Giddens & Slora, 1997). No one really understands why this is, although some researchers believe it could be due to weight differences (Adair & Gordon-Larsen, 2001).
When puberty begins, a girl’s internal clock signals the pituitary gland to begin secreting the hormones FSH and LH, which stimulate the ovaries to produce estrogen while the girl sleeps. Between the ages of 11 and 14, FSH and LH levels begin to increase during the day as well.
As puberty continues, the ovaries, in response to stimulation by the pituitary gland, begin to release more and more estrogen into the circulatory system. Estrogen is responsible for the development and maturation of female primary and secondary sexual characteristics. Under its influence, the Fallopian tubes, the uterus, and the vagina all mature and increase in size. The breasts also begin to develop as fat deposits increase and the elaborate duct system develops. The pelvis broadens and changes from a narrow funnel-like outlet to a broad oval outlet, flaring the hips. The skin remains soft and smooth under estrogen’s influence, fat cells increase in number in the buttocks and thighs, and pubic hair develops. The growing end of certain longer bones in the body, which are responsible for height, fuses with the bone shaft, and growth stops. (In the absence of estrogen, females usually grow several inches taller than average.)
The changes that accompany puberty prepare the woman for mature sexuality, pregnancy, and childbirth. At some point during puberty, usually at about the age of 11 or 12, the woman will begin to ovulate. Most women are unable to feel any internal signs during ovulation. In a few women, however, a slight pain or sensation accompanies ovulation, referred to as mittelschmerz. The pain may result from a transitory irritation caused by the small amount of blood and fluid released at the site of the ruptured follicle. An increase in female sexual interest around this time may be triggered by a rise in various hormones, most notably testosterone (Halpern et al., 1997).
The beginning of ovulation often closely corresponds to menarche (MEN-are-kee) in most girls, though some may begin menstruating a few months before their first ovulation, whereas others may ovulate a few times before their first full menstrual cycle. In the first year after menarche, 80% of menstrual cycles are anovulatory (do not involve ovulation; Oriel & Schrager, 1999).
In some cultures in the past, as soon as a girl reached menarche, she was considered ready to marry and begin bearing children. In our culture, the age of menarche has been steadily falling, and most people believe that there is a difference between being physiologically capable of bearing children and being psychologically ready for sexual intercourse and childbearing. In Chapter 8, we will discuss the psychological and emotional changes of female puberty.