Fertility tests marketed at women worried they have left it too late to have a baby, can be a "waste of money".
Ovarian reserve tests, which can cost £100 or more, measure hormones in blood to give an idea of how many eggs a woman has.
Latest research in the Journal of the American Medical Association found the tests did not predict a woman's chance of conceiving, however.
Women must be told this, experts say.
The tests were originally developed by IVF clinics to predict how a woman having fertility treatment might respond to the drugs used to stimulate the ovaries to produce eggs.
But some companies have been marketing them to women as a fertility MoT.
The JAMA study included 750 women aged 30 to 44 years who had no history of infertility and had been trying to conceive for three months or less.
The results showed that low AMH or high FSH - the hormones that ovarian reserve tests measure - had no bearing on the chance of a woman becoming pregnant within any given month, and did not lead to a lower chance of conceiving after six or 12 months.
Experts point out that many women with low ovarian reserves will conceive without any problems, while others with a good ovarian reserve may take time and need fertility treatment.
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Dr Channa Jayasena, a fertility expert at Imperial College London, said: "Hormone levels change with time, so taking a snapshot today tells us very little about what women's fertility will be like tomorrow.
"This study tells us that measuring these hormones to predict fertility in potentially worried and vulnerable women is wrong, and should be stopped."
He said anyone concerned about their fertility should see their doctor.
The tests might still be useful for investigating women with fertility problems to help decide what treatment to give, experts say.
British Fertility Society president Professor Adam Balen advised: "Fertility does decline as both men and particularly women get older, and so if you start trying for a baby and think there may be problems, or if you've been trying for a year without success, don't delay before seeking advice from a fertility specialist, who will then guide you to the appropriate tests that are right for your personal situation."
Prof Richard Anderson, from the University of Edinburgh, said: "Many more women are concerned about having their first child when older than was the case for previous generations, leading to pressure to seek 'fertility tests'. This paper, confirming smaller earlier studies, shows that we do not have such a thing."
He added: "It's important to note however that this study has only short-term outcomes - the chance of conceiving in the next 6-12 months - and doesn't examine what these tests might tell us about fertility in say five years time."