Caren Erasmus says a magazine article on infertility treatment had a big role in the birth of her son, Shane.

Mrs Erasmus and her husband Ron, of Torbay in Auckland, had been trying to have a baby for more than a year.

"Then a friend told me about an article in Woman's Weekly. That's how I found out about it."

She is referring to a National Women's Hospital infertility-drugs trial, which she entered in November 2003. Within four months she was pregnant with Shane, now 7 months old and "a bundle of joy".

"I would love to have another one," says Mrs Erasmus, aged 31.

While on the trial, which is for women who are infertile because of multiple small cysts on their ovaries, Mrs Erasmus took two drugs: the anti-oestrogen pill clomiphene and metformin, a medicine for type 2 diabetes.

Clomiphene is the established first-line treatment for infertility caused by what is known as polycystic ovary syndrome, but it raises the chances of multiple pregnancy.

The trial is testing metformin as an alternative first-line therapy. Some of the women take both drugs, some take one or the other, and some take a placebo.

Earlier studies have found metformin increases the chances of producing eggs but, unlike this trial, most of them have not assessed the pregnancies and births that may result.

About a fifth of women have the cysts, and about half of that group suffer symptoms such as infertility, obesity, irregular periods, unwanted hair growth and acne.

Most women with the syndrome are also resistant to the hormone insulin, and insulin resistance is the underlying abnormality in most type 2 diabetes.

"A lot of us believe that insulin resistance is the trigger for polycystic ovary syndrome," said the trial's lead researcher, Associate Professor Neil Johnson.

He said the study still had some way to go - more participants were needed - and the researchers did not yet know which drug or drugs most had taken.

Of the 53 women who completed the trial - also running in Waikato, Wellington and Christchurch - 17 have become pregnant. The success rate is higher for those who weigh less in relation to their height.

Dr Johnson said the researchers were also looking for genetic variations among the women, which could help to predict patients' responses to the various treatments.

Making babies

* Trial aims to test the diabetes drug metformin as a first-line therapy for infertility caused by multiple cysts on the ovaries.

* Women are given either metformin, the existing first-line drug clomiphene, both, or a placebo.

* Women close to their ideal body weight are more likely to conceive than women who are obese.

* To take part in the trial, women must have the syndrome, be 18 to 39 and have been trying for a baby for at least six months. Those wishing to take part can phone (09) 373-7599 ext 89487.