Couples trying for a baby may find it easier to conceive if the male takes antioxidant supplements, new research suggests.

A University of Auckland review, published today on the international health care database, Cochrane Library, found men who took antioxidants were more likely to impregnate their partner.

Researchers did not yet know whether different antioxidants performed better than others.

Lead researcher Marian Showell, who works in Obstetrics and Gynaecology at the University of Auckland, said the review focused on 34 trials, involving 2876 couples who were undergoing assisted reproductive techniques.

Most men in the trials had low sperm counts or low sperm motility.

"When trying to conceive as part of an assisted reproductive programme, it may be advisable to encourage men to take oral antioxidant supplements to improve their partners' chances of becoming pregnant," she said.

"However, these conclusions are currently based on limited evidence."

The trials explored the use of many different types of oral antioxidants, including vitamin E, L-carnitine, zinc and magnesium.

"We need more head-to-head comparisons to understand whether any one antioxidant is performing better than any other," she said.