A woman's potential fertility can be predicted from the age her mother went through the menopause, a study has shown.
Ovarian reserve - the number of eggs a woman has left in her ovaries - was found to decline faster in women whose mothers had an early menopause.
The findings suggest that a woman's fertility is, to some extent, inherited from her mother.
Earlier statistical studies had already indicated the trend, but the new research confirmed it by looking at two physical markers of ovarian reserve.
Scientists measured anti-Mullerian hormone (AMH) levels and antral follicle count (AFC) in daughters and compared both with mothers' age at menopause.
Both markers reduced at a faster rate in daughters of mothers who had the menopause early.
<strong>1. Your fertility is mostly determined by genetics, which influences how many eggs you are born with. </strong> Doctors believe that the number of eggs you have at birth determines the length of time you will remain fertile. At birth, women have about two million eggs in their ovaries. For every egg ovulated during your reproductive life, about 1,000 eggs undergo programmed cell death. Other things, such as smoking cigarettes and certain types of chemotherapy, can accelerate egg cell death and promote an earlier menopause.
<strong>2. Regular menstrual cycles are a sign of regular ovulation.</strong> Most women have regular cycles lasting between 24 and 35 days. This is usually a sign of regular, predictable ovulation. Women who do not ovulate regularly have irregular menstrual cycles. Those who do not ovulate at all may have a genetic condition called polycystic ovarian syndrome (PCOS).
<strong>3. Basal temperature charting does not predict ovulation.</strong> An older method of tracking ovulation involves taking your oral body temperature each morning before getting out of bed. This is called basal body temperature. This method is used to spot a rise in basal temperature, which is a sign that progesterone is being produced. The main problem with using this method is that your temperature rises after ovulation has already occurred. This makes it more difficult to time intercourse at an optimal time for conception. A better method is to use over-the-counter urine ovulation predictor test kits such as Clearblue Easy. These kits test for the hormone that prompts ovulation, which is called luteinizing hormone (LH).
<strong>4. Most women with blocked fallopian tubes are completely unaware they may have had a prior pelvic infection.</strong> About 10 percent of infertility cases are due to tubal disease, either complete blockage or pelvic scarring causing tubal malfunction. One major cause of tubal disease is a prior pelvic infection from a sexually transmitted disease such as chlamydia. These infections can cause so few symptoms that you may be completely unaware your tubes are affected. This is why fertility physicians will order a dye test of the tubes, called a hysterosalpingogram (HSG), if you have been trying and failing to conceive for 6 months or longer.
<strong>5. In most cases, stress does not cause infertility.</strong> Except in rare cases of extreme physical or emotional distress, women will keep ovulating regularly. Conceiving while on vacation is likely less about relaxation than about coincidence and good timing of sex.
<strong>6. By age 44, most women are infertile, even if they are still ovulating regularly.</strong> Even with significant fertility treatment, rates of conception are very low after age 43. Most women who conceive in their mid-40's with fertility treatment are using donated eggs from younger women.
<strong>7. Having fathered a pregnancy in the past does not guarantee fertility.</strong> Sperm counts can change quite a bit with time, so never assume that a prior pregnancy guarantees fertile sperm. Obtaining a semen analysis is the only way to be sure the sperm are still healthy!
<strong>8. For the most part, diet has little or nothing to do with fertility.</strong> Despite popular press, there is little scientific data showing that a particular diet or food promotes fertility. One limited study did suggest a Mediterranean diet with olive oil, fish and legumes may help promote fertility.
<strong>9. Vitamin D may improve results of fertility treatments.</strong> A recent study from the University of Southern California suggested that women who were undergoing fertility treatments, but had low vitamin D levels, might have lower rates of conception. This vitamin is also essential during pregnancy. At Pacific Fertility Center, we recommend our patients take 2,000-4,000 IU per day.
<strong>10. Being either underweight or overweight is clearly linked with lowered levels of fertility.</strong> The evidence in recent years is that obesity is clearly linked with a longer time to conception. Having a body mass index less than 18 or over 32 is associated with problems ovulating and conceiving, as well as problems during pregnancy.
Study leader Dr Janne Bentzen, from Copenhagen University Hospital in Denmark, said: "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. However, long-term follow-up studies are required. Conclusive evidence can only be obtained when we have longitudinal studies that follow women who have AMH measurements over time until menopause. Therefore, interpretations of our data are limited and the findings we have described may not occur in any given individual."
The results are reported in the latest online edition of the journal Human Reproduction.
A total of 527 women aged 20 to 40 working in health care at Copenhagen University Hospital took part in the research.
They were divided into those whose mothers had an early menopause up to the age of 45, those whose mothers had a normal menopause between the ages of 46 and 54, and those whose mothers had a late menopause at 55 and older.
Average AMH levels declined by 8.6%, 6.8%, and 4.2% per year in 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% per year in the same groups.
AMH levels and AFC were also significantly lower in contraceptive pill users compared with non-users.
AFC was lowered by an average 11% in women whose mothers smoked while they were pregnant.
Dr Bentzen said the effect of oral contraceptive use was probably temporary and unlikely to influence ovarian reserve in the long term.
However she added: "We believe there is a need for longitudinal, large studies in which ovarian reserve parameters are measured repeatedly in the same individual before, during and after the use of oral contraceptives. Additionally, we need to explore the impact of dose-response and duration of hormonal contraception on markers of ovarian reserve."
In their paper, the researchers wrote: "From a biological point of view, it may be reasonable to assume that a low ovarian reserve may have a long-term effect that will shorten the reproductive lifespan. 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."