Remember that health class you had in middle school? Where you found out all that stuff about your body? We wondered why there wasn't a class like that for middle age. Could someone tell us what happens to us as we move through the decades?

Morning Edition asked listeners to send their questions about women's bodies and aging as part of our ongoing series Changing Lives of Women. We heard from hundreds of you asking about everything from sleeplessness to STDs to sex in old age.

We put your questions to two physicians: Dr. Nanette Santoro, a professor and E. Stewart Taylor chair of obstetrics and gynecology at the University of Colorado School of Medicine, and Dr. Cheryl Iglesia, a professor of obstetrics and gynecology at Georgetown University School of Medicine. Here are their answers, edited for length and clarity.

In my 20s I began getting one or two coarse black hairs on my chin. I jokingly referred to them as "stray eyebrow hairs." But as I've gotten older these hairs have increased and they grow back much more quickly. I'm tweezing at least once a week. Is this normal? — Amanda, 39, Texas

Yes, it is normal and not very well explained. The best explanation is that with aging, we become more insulin resistant. This leads to a decrease in a protein produced by the liver called "sex hormone-binding globulin" or SHBG. SHBG does what it says: it binds up the estradiol and testosterone that women make, and makes them less available to local tissues to do their job.

When SHBG drops, the "free" hormone in your bloodstream goes up in a sense, because it becomes more bio-available to your tissues. This is not a big deal in terms of estradiol, because estrogen is going down with menopause anyway, but testosterone can become more available to your tissues and skin, and is the likely culprit for your increased hair growth. — N.S.

Can you help me understand the roles of hormones and the appropriate levels for my body, age, etc.? I know about estrogen and progesterone. What else? — Denise, 49, South Carolina

Women have three types of reproductive hormones: estrogens (estradiol and its less potent cousins estrone and estriol), progestins and testosterone.

Estradiol is almost exclusively produced by the ovary. After menopause, estradiol levels can become so low that by age 70 or so, a woman is likely to have less estradiol circulating in her body than her same-age husband would have.

Progesterone, a naturally produced progestin, is made all the time in tiny quantities by the adrenal gland. But the ovary makes enormous amounts of it after ovulation, and women are exposed to it during their reproductive years every two weeks. There is no known appropriate level for progesterone in women, as no one knows exactly how much is needed after ovulation. If a woman is getting regular menstrual periods, she is very likely to be making adequate quantities of both estradiol and progesterone.

Testosterone's role is less well-defined in women. Women need some circulating testosterone to have normal ovulation, as the ovary takes up the testosterone and "feeds" it to the growing follicles, so they can produce estrogen. Beyond that, testosterone is believed to possibly drive libido in women, but this is not a very powerful effect for most women. (Sometimes testosterone is used as a treatment for low libido in women.)

As women age, their overall production of testosterone drops. The most dramatic drop is 10 to 15 years before menopause. There are some conditions in which women make too much testosterone. The common disorder of polycystic ovary syndrome, which affects about 5 to 7 percent of adult women, is such an example. In this case, the testosterone may disrupt the menstrual cycle and interfere with a woman's ability to ovulate, not to mention cause other problems like acne and excessive body hair. — N.S.

Does the decision not to have children affect my reproductive health and is there anything I can do to keep it in tip-top shape through the years? — Carolanne, 28, Oregon

Yes, there are things you can do. Not getting pregnant before age 30 can increase your risk of breast cancer, and nulliparity (no pregnancies) increases your risk of ovarian cancer. Tip-top shape requires a proactive approach. Maintain a healthy lifestyle and weight with healthy eating, adequate exercise and sleep. Oral contraceptives can protect against breast cysts and actually lead to decreased ovarian cancer, if taken for 10 years or more. Also, breast self-awareness and screening mammograms should be conducted at intervals based on your age and individual risk factors. — C.I.

So, kegels — you know, the things I should have been doing forever but didn't? Now I know why I should have done them. Can I make up for lost time or is it a lost cause? — Amelia, 48, Colorado

Kegels (pelvic floor muscle exercises) are important in maintaining bowel and bladder function and sexual satisfaction. Here is how they are done. A health care provider or physical therapist can help if you think you are not doing the exercises correctly. — C.I.

There is so much so much conflicting information about fat loss, specifically on women's hips. Could someone answer, once and for all, how to get rid of that stubborn fat that Mother Nature "gifted us"? Some of us want a gift receipt. — Cassidy, 25, Kentucky

Alas, there is no formula that will eliminate the accumulation of midbody fat with aging. As we age, we all become more insulin resistant and tend to accrue fat in the hips and waist. To boot, menopause is associated with a small increase in waist girth in most women. The best way to combat this increase is exercise, and women have to up their game in midlife to stay in the same place. When all else fails, there's always liposuction! — N.S.

I have started to skip periods. Does that mean I'll go into full menopause within the next few years? Or will I keep having periods for 10 more years? What are the real signs that you're almost done? — Jerrilyn, 44, Oregon

The menopause transition is divided into two stages — early and late. The early transition is marked by relatively isolated skipped periods, such that a woman does not go more than 60 days without a bleed. This stage can be very variable. If that is where you are at age 44, it's quite possible that you won't be fully menopausal (one whole year without a period) until you are 50 or so.

The median age at menopause is 51.4 years. However, if you enter the late transition stage and are more than 60 days without a bleed, that usually means you are going to be fully menopausal within 4 years. — N.S.

Does menopause end? When and why do the hot flashes and mental fog go away? — Anonymous, 52, Washington, D.C.

While the onset of menopause is easy to define, the end is far more squishy.

For most women, the first five years are the most symptomatic, but for up to 20 to 40 percent of women, depending on their particular physiology, hot flashes can last for 10 years. And for about 10 percent of women, they just keep going on and on.

The most characteristic mental symptom that women experience is short-term recall loss, which partially comes back (but doesn't go back to what it was before the transition started). Some women experience a loss in "executive function" and have difficulty with organizational tasks, and there is some evidence that this may be treatable with medication used for adult ADHD.

Poor sleep and depression can also co-exist with menopausal symptoms, and these problems will also contribute to mental fog-type symptoms. Treating the primary problem can help. — N.S.

I'm taking antidepressants and have little sex drive. How do I strengthen it? — Regina, 49, Illinois

Decreased libido is common during perimenopause, the transitional period before menopause. Flibanserin (Addyi) is the new FDA-approved drug for hypoactive sexual desire disorder in premenopausal women. Some antidepressants like SSRIs (including Prozac, Zoloft and Lexapro) are associated with decreased libido. Ask your doctor if you can switch to a different medication (like bupropion — Welbutrin). Strengthening the relationship with your partner to improve communication can often be very helpful in midlife. — C.I.

What can young women do to deter osteoporosis and improve joint health for later in life? When should women start working to preserve bone health? — Britt, 31, Texas

You can't start early enough. Women should pay attention to their calcium intake and ideally take in about 1,000 mg a day from dietary sources when they are premenopausal. After menopause, unless a woman is taking estrogen, her calcium needs go up to 1,200 mg a day. Vitamin D is also important to maintain. It's fairly easy to find the calcium content of commonly eaten foods on the Web; I like to refer my patients to the , which links to several sources.

Taking a calcium supplement is reasonable if calcium intake is very low due to dairy intolerance or other reasons, but it's important not to overdo it. Too much calcium supplementation has been linked to a small but increased risk of heart disease. — N.S.

I have endometriosis and I'd like to know what I can expect as I age. Will going into menopause essentially "cure" the endometriosis? — Holly, 41, Massachusetts

Endometriosis affects about 3 to 5 percent of women and happens when the inner lining of the uterus, the endometrium, starts to grow within the pelvis. It tends to "burn out" and improve with menopause. If a woman has had multiple surgeries and has less ovarian tissue remaining, she may go through menopause earlier than normal. Many women with endometriosis tend to have menopause slightly earlier. Women with endometriosis can take hormones after menopause if their disease is not active, but it is recommended that they take estrogen with progesterone to prevent endometriosis growth, even if they have had a hysterectomy. — N.S.

What is the current practice on taking hormones for transgender women as they enter what would be the menopause years? Keep taking estrogen? Gradually decrease? — Alison, 42, Minnesota

Theoretically, a trans woman will have been exposed to estrogen for fewer years in her life, and might be able to extend the time during which she takes hormones. But there is not a lot of knowledge about how the long-term risks may play out in trans women. Therefore, current guidelines for trans women are similar to women who have been exposed to estrogen for their entire lives. In general, there is no reason to take hormones after the age of about 50 unless menopausal symptoms are present. — N.S.

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