Menopause is defined as the date 12 months after a woman's last menstrual period. The average age for American women to reach menopause is 51 with a normal range of 39 to 59 years of age.
At menopause, estrogen production slows. The earlier this occurs, the greater the risk to the heart and bones. But prolonged estrogen exposure also carries risks, particularly in higher breast and ovarian cancer rates, according to the North American Menopause Society.
Ovarian Cancer Risk
There are advantages to late menopause. Women who experience menopause after age 52 have a longer life expectancy, according to a 37-year study of women in Norway reported in the October 2003 issue of the "American Journal of Epidemiology." This is because cardiovascular disease, the most common cause of death among American women, is prevented, to a degree, by the presence of estrogen, which diminishes at menopause.
Although generally the later menopause starts the better off the woman's health will be, there are risks caused by prolonged exposure to estrogen and the primary one is ovarian cancer. This risk is particularly strong if menarche, the beginning of menstruation, was early and if the body had no breaks from estrogen exposure through pregnancy and breastfeeding, according to the May 2010 National Cancer Institute's Guidelines for Risk Evaluation.
One group of women are at particular risk from late menopause. These ladies have cumulative risks started with an early start of menstruation, before age 12. They never had a full-term pregnancy despite repeated attempts to conceive using fertility medications, and then they went into menopause late. If they also carry the genetic predisposition for ovarian cancer, their risks are even higher, according to the ACOG.
Allowing estrogen levels to fall naturally at menopause rather than using hormone replacement therapy should be considered by high risk women and their care providers. Likewise, in accord with the ACOG Guidelines, high risk women should achieve and maintain a body mass index of less than 25 and a waist circumference of less than 35 inches. This is because fat produces estrogen and obesity is an added risk factor for ovarian cancer.
Breast Density and Late Menopause
Breast tissue density is an independent risk factor for breast cancer and is associated with higher levels of estrogen exposure as well. Women with very dense breasts who have a prolonged menstrual history including those with either late natural menopause or those who prolong their premenopausal years with hormone replacement therapy compound this risk, according to research by Celia Byrne, Ph.D., of Georgetown University. Dr. Byrne's team examined mammograms from the Women's Health Initiative and found that women with high breast density were most at risk of breast cancer. Breast density drops dramatically at menopause which means that women with high density and late menopause have the compound factors that elevates their risk.
A woman with dense breasts who reduces her BMI to less than 25 and her waist circumference to less than 35 inches will drop her estrogen levels, lowering her breast cancer risk, according to Dr, Bryne's study.
ACOG guidelines call for women and their health care providers to determine breast density by mammogram and then to consider this information when deciding whether to use hormone replacement therapy at menopause. This is especially true for women with late menopause who often have higher estrogen levels and denser than average breasts.
Pregnancy and Delayed Menopause
In 2007, six out of every 10,000 live births in the United States were to women age 50 to 54, a 5 percent increase from 2006, according to the National Center for Health Statistics.
Even when using donor eggs and invitro-fertilization it is rare for a woman to become pregnant and not miscarry after age 45, but it does happen. And sometimes it happens without assistance, other than that of the child's father, at all.
The most common complication in women who conceive as a result of delayed menopause is miscarriage. Women over age 42 have a greater than 50 percent risk of miscarriage if they conceive.
Other risks, noted by the National Institutes of Health, are greatly elevated in after-50 pregnancies as well, including diabetes, preeclampsia and other forms of high blood pressure and choriocarcinoma, a pregnancy related cancer.
Children conceived by elder moms face an elevated risk of Down Syndrome and other congenital disorders compared to those who's mothers are under 45 at conception. They are also more likely to be born prematurely and to be small for their gestational age at birth.
Women wondering when they can stop using birth control should be aware that conception is possible until a full year after the last menstrual period, the reason ACOG and other associations choose this date as the official time of menopause.
- North American Menopause Society: What is Menopause
- "American Journal of Epidemiology"; Age at Natural Menopause and All-Cause Mortality; Bjarne K. Jacobsen, Doc. Med Sci. et al; October 2003
- National Cancer Institute: Risk Factors for Ovarian Cancer
- American Assoc of Cancer Research: Report to the 101st General Meeting: Celia Byrne, M.D..et al: June 2010
- ACOG: Pause, A Thoughful Woman's Guide to HRT: 2009