(RxWiki News) Women are their mothers' daughters, even at the point in life when they can't have children anymore.
The age women hit menopause may be the age their daughters start it in the future, a new study has found, as measured through their levels of anti-Müllerian hormone (AMH) and the number of eggs in their ovaries.
"This is the first study to suggest that the age-related decline of AMH and antral follicle count (AFC) may differ between those whose mothers entered menopause before the age of 45 years and those whose mothers entered menopause after the age of 55 years," the lead author said in a press release.
"Time to get pregnant? Get an AMH test."
Researchers, led by Janne Bentzen, MD, PhD, from the Department of Obstetrics and Gynecology at Copenhagen University hospital in Denmark, looked at 527 women who worked in health care at the Copenhagen University Hospital between September 2008 and February 2010.
They ranged between 20 and 40 years of age. The age their mothers started menopause was known.
Researchers divided the women based on when their mothers started menopause naturally and asked each participant about her smoking habits, body mass index and use of oral contraceptives.
The mothers of the first group had menopause younger than 45, the second went through it between 46- and 54-years of age and the mothers of the last group had it after they turned 55. Researchers counted the number of astral follicles in the participants' ovaries using a special sonographer and measured the amount of anti-Müllerian hormone in their blood.
Small follicles in the ovaries make AMH as they grow. The more present the hormone, the more eggs present.
They found the earlier participants' mothers had menopause, the sooner their ovaries were depleted. Participants' AMH levels declined at a higher percentage the earlier their mothers had menopause. Each year, AMH levels went down 8.6, 6.8 and 4.2 percent for the women with mothers who had early, normal or late onset respectively. The number of follicles in the ovaries also went down 5.8, 4.7 and 3.2 percent respectively along the same pattern.
"Epidemiological studies have established a link between the age at menopause among mothers and daughters," Dr. Bentzen said in a press release.
"In line with the suggested 20-year interval between the first decline in fertility and the menopause, we hypothesized maternal factors may also have an impact on a woman's fertility potential in terms of ovarian reserve."
Researchers also found women who use oral contraceptives had about 27 percent lower levels of the hormone and follicle count than those who aren't on the pill. Using oral contraceptives probably has a temporary effect on women's eggs, according to Dr. Bentzen.
Future studies should look at how the size of the dose and how long the pills are taken affects the ovarian reserves.
In addition, smokers have 11 percent fewer follicles than women who don't smoke, but hormone levels didn't have any significant differences between the groups. The researchers did not find whether a mother's age at menopause is directly linked to how old the daughter will be when she can no longer have kids.
"…It may be reasonable to assume that a low ovarian reserve may have a long-term effect that will shorten the reproductive life span," the authors wrote in their report.
"We therefore assume that markers such as ‘maternal age at menopause’ in combination with AMH or AFC, and chronological age may represent a more complete picture when evaluating the ovarian reserve of the individual."
The authors note that because the participants work in health care, they may be more aware of living healthy compared to the general population.
The participants may also have reported the start of their mothers' menopause as a more ideal age, and the women were not grouped randomly. The study was published online November 6 in the journal Human Reproduction. The authors did not declare any conflicts of interest. The Danish Agency for Science, Technology and Innovation, Copenhagen Graduate School of Health Science (CGSHS) and the Fertility Clinic at Copenhagen University Hospital supported the study.