"'Fertility MOTs' are a waste of money," reports The Daily Telegraph after researchers in the US found hormones tested in "ovarian reserve" fertility test kits bear no relation to how likely women were to get pregnant – at least, in the early months of trying to conceive.
These tests usually measure the levels of three hormones:
- anti-mullerian hormone (AMH)
- follicle-stimulating hormone (FSH)
- inhibin B
All of these hormones have been linked to measures of a woman's "ovarian reserve" – how many viable eggs she has left in her ovaries.
Researchers analysed hormone levels from 750 women aged 30 to 44 who'd been trying to get pregnant for three menstrual cycles or less.
They followed the women for 12 cycles to see how many got pregnant.
After taking account of factors including the women's age, they found hormone levels didn't affect the women's chances of becoming pregnant in any given cycle.
Levels of AMH decline over time and become undetectable at menopause, when a woman's egg supply is exhausted.
But the results of this study suggest it doesn't matter how many eggs a woman has in reserve to get pregnant – as long as she's still releasing eggs regularly.
There seems to be little reason for women to be offered these tests, which can cost more than £100 a time, unless they're undergoing fertility treatment, when the tests are used to help plan and predict IVF results.
Where did the story come from?
The study was carried out by researchers from the University of North Carolina, the University of Southern California, Duke University, the National Institute of Occupational Safety and Health, and the National Institute of Environmental Health Science, all in the US.
It was funded by the US National Institutes of Health.
The study was published in the peer-reviewed Journal of the American Medical Association (JAMA).
The UK media's reporting was reasonably accurate and balanced. Most headline writers focused on the cost of the tests, describing them as a "waste of money".
But the tests could also cause unnecessary emotional distress if they wrongly suggest a woman's fertility is lower or higher than it actually is.
What kind of research was this?
This prospective cohort study set out to learn whether women with high or low levels of specific hormones were more or less likely to get pregnant over a given period of time.
This type of study is useful for showing us whether there's a link between one factor (hormone levels) and another (pregnancy).
What did the research involve?
Researchers recruited 981 volunteers to take part in the study. After excluding those who didn't meet the criteria or withdrew or got pregnant before the study started, 750 women were left.
The women filled out questionnaires, and had blood and urine samples taken to test their hormone levels.
They also filled out diaries documenting menstrual bleeding, when they had sex, and the results of pregnancy tests.
The women were followed up for 12 months. Researchers adjusted their figures to take account of confounding factors, and then looked at whether hormone levels were linked to the women's chances of getting pregnant after 6, 12, or any given cycles.
Women were only included in the study if they were aged 20 to 44, had been trying to get pregnant for three cycles or less, had no history of fertility problems, and were living with a male partner.
Researchers defined normal AMH as above 0.7ng/ml, based on previous research. Normal FSH – which is higher in older women – was defined as below 10mIU/ml.
It's not currently clear if there's such a thing as a normal inhibin B level and what that would be, so the researchers considered this a continuous variable.
The outcomes measured were the cumulative probability of conception (measured by a positive pregnancy test) after 6 or 12 menstrual cycles.
The researchers took account of these potential confounding factors:
- body mass index
- smoking status
- use of hormonal contraceptives in the past year
What were the basic results?
Of the 750 women in the study, 65% got pregnant, 17% didn't get pregnant, and the remainder dropped out before 12 months (for example, because they started fertility treatment).
After adjusting for confounding factors, the predicted probability of getting pregnant after 6 or 12 cycles wasn't lower for women who had low AMH or high FSH, and wasn't linked to inhibin B levels.
Looking at AMH:
- 65% of women with low AMH were predicted to get pregnant within six cycles, compared with 62% with normal AMH
- 84% of women with low AMH were predicted to get pregnant within 12 cycles, compared with 75% with normal AMH
- the chances of getting pregnant in any given cycle was no different for women with low and normal levels of AMH (hazard ratio 1.19, 95% confidence interval 0.88 to 1.61), so the result wasn't statistically significant
Researchers also looked at different age groups to see if hormone levels made more of a difference to younger or older women. They found low AMH wasn't linked to lower chances of pregnancy in any age group.
How did the researchers interpret the results?
The researchers said their results were "surprising". They'd anticipated there would be a difference in fertility levels by hormone level, but say the results suggest there "may be little association between a woman's ovarian reserve and factors affecting fertility, such as egg quality".
They said their findings "do not support the use of urinary or blood FSH tests or AMH levels to assess natural fertility" for women aged 30 to 44 without fertility problems who have been trying to get pregnant for three cycles or less.
Anxiety about getting pregnant, especially at older ages, is common, and women may feel pressured into taking so-called "fertility MOT" tests to see whether they've left it too late.
But the results of this study strongly suggest that these tests don't predict how easily or quickly a woman will be able to get pregnant.
Some women may use the tests to find out whether they can delay pregnancy, and take a result showing a high ovarian reserve to mean that they have plenty of time to get pregnant.
But the tests only give a snapshot of ovarian reserve at one point in time – they don't tell you how quickly the levels may change in future.
The researchers may be right that other factors, such as egg quality or the quality of a partner's sperm (which also declines with age), are more important – as long as the woman is regularly releasing eggs.
The study was well-designed and carried out, but has some limitations.
For one, the researchers measured pregnancy rates, not birth rates. It's possible that hormone levels could affect the chances of a woman carrying a baby to term, although there's no research to suggest this is the case.
It's also important to remember that these women were all in the first few cycles of trying to get pregnant. The results may not be the same for women with known fertility problems.
There's no doubt that women do find it harder to get pregnant as they get older.
Women who want to get pregnant and have been unable to do so within six months of trying should see their doctor to find out whether there's a problem.
Women being investigated for fertility problems may well need to have these tests, which help plan and predict the success of IVF treatment.
Women who have just started trying for a baby and have no known fertility problems should probably save themselves the money and stress.
Analysis by Bazian
Edited by NHS Website
Links to the headlines
The Daily Telegraph, 10 October 2017
BBC News, 10 October 2017
The Independent, 10 October 2017
Links to the science
JAMA. Published online October 10 2017