More Orthodox couples are considering radical ways to get pregnant, including surrogacy and sperm donation, with medical experts advising that these treatments can be compatible with Jewish law.

Dr Simon Fishel, a leading fertility specialist, said rabbis were open to new kinds of treatment, but couples were often subjected to traumatic conflicting advice.

He said: "These are areas of great ethical debate, even in the secular world. Judaism is a really positive religion when it comes to modern medicine. But the debate can cause real discrepancies and can be very confusing."

He pointed to the issues of sperm donation and surrogacy. Some rabbis have previously recommended that women should only choose non-Jewish sperm donors - to prevent the risk that the child could grow up and accidentally marry a half-sibling.

Dr Fishel said: "Some rabbis will think this is totally unethical, but some will encourage it. It's also an issue in surrogacy - should the surrogate be Jewish?

Sensitivity is vital, not least if the rabbi has a big family

"There's also a cornerstone of Jewish law which says a child must know its parents. And that means surrogacy and donors cannot be kept secret. If they are, it can cause huge problems in the family."

Among the strictly Orthodox community, fertility issues have long been a taboo subject. But last week at a remarkable Orthodox conference, the first of its kind run by fertility charity Chana, rabbis and doctors discussed new, radical advances in treatment. Organisers believe this shows a new appetite to understand a common problem.

During the conference, 70 rabbis and dayanim held a closed meeting with Dr Fishel to debate core issues in fertility. Carolyn Cohen, support worker at Chana, said the session had been about learning the science, not making pronouncements about halachah.

Dr Fishel said: "The rabbis I spoke to at the conference were very empathetic and realised the magnitude of the issues. In this community, there is more stress on the need to have a family as people believe it is a divine commandment to have children."

Devorah Cohen, another of Chana's support workers, said: "It's important that people realise that assisted reproduction is OK in halachah. We want people to be able to have a family and rabbis will assist in making that possible as much as they can. "

Rabbi Yehuda Pink, of the Jewish Medical Ethics Forum, advised that rabbis should realise when they are out of their depth.

"The more knowledgeable a rabbi, the more he will try and find a way to make it work for the couple. It's very easy to forbid something you don't understand. The other important thing is sensitivity; many rabbis have large families and that can make a couple very uncomfortable talking about problems getting pregnant."