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Mum's menopause may predict daughter's fertility
Study finds hereditary factors may help predict how many eggs a woman still has
7th November 2012 - Women concerned about their fertility may be able to gauge it better by knowing their mother's age at menopause.
A Danish study published online in the journal Human Reproduction found women whose mothers had an early menopause had far fewer eggs in their ovaries than those whose mothers had a later menopause.
The number of eggs remaining in a woman’s ovary is related to her ability to conceive naturally, with both the number and quality of eggs starting to decline as she gets older. As couples in Europe have in recent times postponed childbearing this study may be something worth taking into consideration if you are concerned about fertility.
Researchers assessed ovarian reserve (how many eggs a woman has remaining) with two accepted methods: levels of anti-Müllerian hormone (AMH) a hormone produced in the ovaries and released into the blood and antral follicle count (AFC) studying the structures in the ovary that release eggs.
These results for daughters were compared with the age of menopause in their mothers. Both AMH and AFC declined faster in women whose mothers had an early menopause compared to women whose mothers had a late menopause.
Dr Janne Bentzen from the Copenhagen University Hospital, who led the research, said in a press statement: "This is the first study to suggest that the age-related decline of AMH and 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. Our findings support the idea that the ovarian reserve is influenced by hereditary factors."
Previous research has suggested that there is about 20 years between a woman’s fertility starting to decline and the onset of menopause. So a woman who enters the menopause at 45 may have experienced a decline in her fertility starting at the age of 25.
The researchers recruited 527 health care workers from the Copenhagen University Hospital, who were aged between 20-40 years and whose mothers’ age at natural menopause was known. They divided them into three categories: those whose mothers had an early menopause (younger than 45); normal maternal age at menopause (46-54 years); and late maternal age at menopause (older than 55).
They used transvaginal sonography, an ultrasound examination of the ovaries conducted through the vagina, to count the number of antral follicles in the women’s ovaries. Follicles are clusters of cells that contain the immature egg. Every woman is born with about two million of them, but only 400 will ever mature enough to release an egg for fertilisation during a woman’s reproductive lifespan. Levels of AMH were measured from blood samples.
After adjusting for various factors that could affect the results (e.g. smoking, contraceptive use, age and BMI), they found that average AMH levels declined by 8.6%, 6.8% and 4.2% a year in the groups of women with mothers who had early, normal or late menopauses respectively. A similar pattern was seen for AFC, with annual declines of 5.8%, 4.7% and 3.2% in the same groups respectively.
The study authors say they 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 a woman's ovarian reserve.
However, they recognise their assumption needs further studies before it can be put to the test.