Taking antioxidant supplements appears to have no effect on a woman's chances of getting pregnant, research has shown.
Many women undergoing fertility treatment take the pills in the belief that they might help them to conceive.
But a study of data from 3548 women attending fertility clinics found no evidence that supplements increase pregnancy or birth rates.
Women taking antioxidants were no more likely to conceive than those taking "dummy" placebo pills or receiving standard treatments, such as folic acid.
Findings from the review of 28 trials appear in The Cochrane Library, which publishes reports on treatment effectiveness.
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Lead researcher Dr Marian Showell, from the University of Auckland in New Zealand, said: "There is no evidence in this review that suggests taking an antioxidant is beneficial for women who are trying to conceive."
Women suffered no harm from taking the supplements, according to 14 trials which reported on adverse effects such as miscarriage and ectopic pregnancy.
