Your "Real" Reproductive Age
Up until 2001, there were no clinical guidelines to characterize our reproductive life span. Finally, representatives from esteemed organizations, including the American Society for Reproductive Medicine (ASRM), the National Institutes of Health, and the North American Menopause Society, pooled their knowledge and developed the STRAW system. STRAW stands for the Stages of Reproductive Aging Workshop in which it was developed, under the direction of Dr. Soules.
The beauty of STRAW is that you can get a sense of what stage you are in based on your menstrual patterns, symptoms, and the overall characteristics of a stage, rather than just a certain hormone range or chronological age. Looking at the whole picture makes it clearer that reproductive capacity is unique for each individual, explains Dr. Soules. After all, there are a great number of variables in each woman's genetic makeup, health, and lifestyle habits that carry her more quickly or slowly from one reproductive stage to another.
Even the stages designated by STRAW aren't set in stone. "While most women will progress from one stage to the next, some will seesaw between stages or skip a stage altogether," says Dr. Soules. It's also important to keep in mind that although normal menopause occurs between 42 and 58, the age ranges in STRAW are based on the average age of 50 (so you can feasibly be up to 8 years ahead of or behind the curve).
Note that while the stages are based on the STRAW model, our experts not affiliated with STRAW have also commented on fertility issues to be aware of at each stage.
Early Reproductive Stage
Approximate age: Puberty to age 20
Hormone levels. Your FSH and estrogen are within normal range (although you probably have no reason to have them tested).
Characteristics: Following your first period, your menstrual cycles may take several years to fall into the 28- to 31-day pattern that you can expect for the majority of your reproductive years. Your hormone feedback system may not be strong enough to always induce ovulation, which is one reason why sexually active women in this stage are slightly less fertile than their more mature sisters.
Fertility issues: "Women in this generation are the only group whose smoking rates are on the rise. That's very bad news, because you may be killing off without any trace a substantial number of eggs that you'll wish you had 15 years down the line, especially if you expect to delay childbearing," says Dr. Tilly.
Stage-specific advice: Single, teen mothers are the most economically disadvantaged group in the nation. "Planning childbearing with your career in mind and waiting for a supportive partner are perfectly legitimate reasons to delay childbearing," says American culture scholar Margaret Marsh, Ph.D., professor of history and dean of the faculty of arts and sciences at Rutgers University in Camden, New Jersey, and coauthor of The Empty Cradle: Infertility in America from Colonial Times to the Present.
Middle Reproductive Stage
Approximate age: 20 to 38
Hormone levels: Your FSH and estrogen are within normal range (you might want to get a baseline test at around age 35).
Characteristics: Your menstrual cycles should be regular throughout this stage. One percent of the female population, however, experiences menopause before the age of 40, where FSH levels prematurely increase and menstrual cycles stop.
Fertility issues: This is the longest of all the stages. It's actually broken into three segments. The first 7 years are your peak fertility time; the next third marks your first slight fertility decline, followed by the beginning of your second fertility decline, around age 35. (The sharpest statistical drop in fertility, however, occurs at the age of 45, according to the U.S. Census Bureau.)
Stage-specific advice: Sexually transmitted diseases (STDS) are highest among women in their twenties, and they're the leading cause of infertility for this generation. "The greatest long-term fertility advice we doctors can give is to avoid STDs by practicing safe sex," says Wanda Ronner, M.D., a gynecologist at Pennsylvania Hospital of the University of Pennsylvania Health System in Philadelphia and coauthor with Dr. Marsh of The Empty Cradle: Infertility in America from Colonial Times to the Present.
Late Reproductive Stage
Approximate age: 38 to 42
Hormone levels: Your FSH levels may have jumped from around 5 mIU/mL to closer to 15 or 20. If a test indicates that your FSH levels are normal and you're already 40, have the test taken a second time, since levels in this stage tend to fluctuate from month to month.
Characteristics: Although your FSH levels may have increased, you probably still ovulate and menstruate on your usual 28- to 31-day schedule. But since your follicles are getting less responsive to FSH, they may produce less estrogen. As the body's estrogen receptors take note, you may become more sensitive to extreme temperatures or even experience hot flashes. Since lower estrogen levels affect the elasticity and acidity of the vagina, you may need a lubricant during sex or develop more yeast and bladder infections than you did in younger years. Even if you didn't get PMS in the past, you're now more likely to experience mood swings and discomfort around the time of your period.
Fertility issues: Your natural increase in FSH may be so stimulating to the ovary that it brings more than one egg to maturity. That's why if you were to get pregnant in your late thirties, you're more likely to have multiple births! (This probability drops off in your forties, unless you use fertility drugs, which also promote multiple births.) And since birth defects increase in women over 35, you are advised to consider genetic counseling before conceiving.
Stage-specific advice: "The first sign of elevated FSH is a call to accelerate your childbearing plans, particularly if you wish to conceive without medical intervention in the future," says Dr. Metzger. To maintain your ovulation consistency, you may want to consider natural supplements such as vitex or, if you are currently trying to conceive, a prescription for clomiphene citrate (Clomid).
Early Perimenopausal Stage
Approximate age: 42 to 46
Hormone levels: Your FSH may have doubled from the last stage, up to around 30 mIU/mL. Estrogen could be declining (under 80 pg/mL) due to lower follicle quantity and quality, or it may be temporarily elevated (above 100 pg/mL) in an attempt to modulate high FSH.
Characteristics: As you get deeper into the menopausal transition, not only is the follicle releasing less estrogen, it's also skimping on progesterone, which normally soars in the second half of your cycle. With only moderate amounts of estrogen stimulating the uterus, and no progesterone, there's less uterine lining to shed, and you do so earlier in your cycle. Consequently, your cycles may shorten to 24 to 27 days instead of 28 to 31, and your periods might be heavier or lighter than they used to be.
Fertility issues: Pregnancy and labor may require more medical attention for women over 40. You are almost twice as likely to have a cesarean birth as younger women, have a 7 percent chance of developing gestational diabetes (compared to 1.7 percent for a woman in her twenties), and are more likely to experience high blood pressure in pregnancy (even if you didn't have it already). Hopefully, you've kept up with a fitness program and optimized your nutrition as part of your preconception care plan -- which can help you beat the odds for high-risk pregnancies, says Dr. Minkin.
Stage-specific advice: Whether or not you have opted to use medical intervention like fertility drugs or in vitro fertilization (IVF) to increase your chances of conception, make sure you ask your doctor about taking progesterone to help the uterine lining build up enough for a fertilized egg to implant and stick, urges Dr. Metzger.
Late Perimenopausal Stage
Approximate age: 46 to 50
Hormone levels: Your FSH levels continue to climb, typically as high as 50 mIU/mL.
Characteristics: Even if your very high FSH successfully stimulates a follicle to mature, that follicle can be "deaf" to the next signal down the line, which is LH and its cohort hormones telling it to release the egg. Expect ovulation to be hit or miss -- this stage is characterized by two or more skipped menstrual cycles. And then, just when you thought you could stop clipping tampon coupons, your period might come back. It may be a "phantom period" where you don't ovulate but still have some endometrium to shed, or you may resume your old ovulation pattern for a few more months or years. The less frequently you ovulate, the less estrogen you produce -- which often means more noticeable perimenopause symptoms.
Fertility issues: Mentally prepare yourself for pregnancy loss, since half of pregnancies to women over 45 end in miscarriage. "And since childbirth is more aerobic than a half marathon, it's essential that you are physically 'trained' before conceiving. At the least, try to walk 3 miles every other day," says Dr. Minkin.
Stage-specific advice: "When considering if you have what it takes to raise the child to adulthood, apply the hoop-shooting rule: Ask yourself if you will be energetic and fit enough to shoot hoops with your child on their 13th birthday," Dr. Minkin advises.
Menopause and Postmenopausal Stage
Approximate age: 50+
Hormone levels: Your FSH levels will reach their peak, between about 50 and 70 mIU/mL, where they will stay. Your ovaries significantly decrease their production of estrogen, although the adrenal glands continue to produce small amounts.
Characteristics: Once you haven't had a period for an entire year, you're officially in menopause. You can now be almost certain of not flip-flopping back into a surprise ovulatory cycle. Of interest, you may still have a few hundred or even a few thousand eggs in your follicles, but the last few hundred generally don't develop.
Fertility issues: Your last option for getting pregnant now may be the high-tech medical intervention of using a donor egg with an IVF treatment -- that is, if you have the financial capability and your doctors think you're likely to respond. When over-40 women undergo IVF with younger women's eggs, they actually have very similar conception rates as younger women. In order to truly "level the playing field," though, older women may need to have more embryos transferred than younger women would and take progesterone along with standard fertility drugs.
Stage-specific advice: The ASRM advises women to have counseling to understand the full legal, ethical, psychological, and social issues involved with using donor eggs or sperm. In fact, RESOLVE: The National Infertility Association recommends that both the couple receiving the egg and the donor of the egg work with a lawyer.
Reprinted from: Stay Fertile Longer: Everything You Need to Know to Get Pregnant Now -- Or Whenever You're Ready by Mary Kittel with Deborah Metzger, M.D., Ph.D. ? 2004 by Rodale Inc. (September 2004; $13.95US/$19.95CAN; 1-59486-053-X) Permission granted by Rodale, Inc., Emmaus, PA 18098. Available wherever books are sold or directly from the publisher by calling (800) 848-4735 or visit their website at www.rodalestore.com
Mary Kittel is a seasoned health writer and coauthor of numerous books, including The Hormone Connection and Prevention's Ultimate Guide to Women's Health and Wellness.
Deborah Metzger, M.D., Ph.D., is a leading expert in the field of fertility and reproductive health. She is medical director of Helena Women's Health in San Jose, California, and was previously associate professor at the University of Connecticut Health Center. She is an advisor to the national Endometriosis Association and has lectured extensively throughout the world.