WEDNESDAY, Nov. 7 (HealthDay News) -- A mother's age at menopause may predict her daughter's fertility in terms of eggs remaining in her ovaries, a new study suggests.

For the study, researchers divided more than 500 Danish women, aged 20 to 40, into three groups: those whose mothers had an early menopause (younger than 45); normal menopause (46 to 54 years); or late menopause (older than 55).

The research team assessed the number of eggs in the women's ovaries using two accepted methods: levels of anti-Mullerian hormone and antral follicle count determined by sonography. Follicles contain the immature egg. They found that both declined faster in women whose mothers had an early menopause than in those whose mothers had a late menopause.

After adjusting for other factors such as smoking, contraceptive use, age and body mass index, the researchers found that average anti-Mullerian hormone levels declined by almost 9 percent, 7 percent and about 4 percent a year in the women whose mothers had early, normal or late menopause, respectively.

Antral follicle count declined almost 6 percent, 5 percent and about 3 percent in the same groups, respectively, according to the study, published Nov. 7 in the journal Human Reproduction.

The number of eggs remaining in a woman's ovaries affects her ability to conceive naturally, and both the number and quality of eggs decline as women age.

"Our findings support the idea that the ovarian reserve is influenced by hereditary factors. However, long-term follow-up studies are required," study leader Dr. Janne Bentzen, from the Copenhagen University Hospital, said in a journal news release.

The researchers also found that anti-Mullerian hormone levels and antral follicle count were significantly lower in women who used birth control pills, compared to non-users. In addition, antral follicle count in women whose mothers smoked while they were pregnant was an average of 11 percent lower, but anti-Mullerian hormone levels were not significantly different.

The effects of birth control pills are likely to be temporary and unlikely to influence the long-term decline in ovarian follicles, Bentzen said. But, she added, doctors and women should be aware of this effect when considering women's reproductive life spans or any fertility treatment.

More information

The U.S. National Institute of Child Health and Human Development has more about fertility/infertility.