By Ania Lichtarowicz BBC health reporter in San Antonio, Texas

Women undergoing fertility treatment in New York during the 11 September attacks may never be able to have children.

Almost 3,000 died - and others may never be born

The finding was announced presented at the meeting of the American Society for Reproductive Medicine in San Antonio, in Texas.

Doctors believe that stress caused by the attacks on the World Trade Center in 2001 may have left some women infertile.

Out of nearly 400 fertility patients treated at a Manhattan clinic, women who found out they were pregnant after 11 September were 25% more likely to miscarry than those who knew before the attacks that they were expecting a baby.

Dust and smoke may have affected the health of the women.

But Steve Spandon, from the Centre for Reproductive Medicine and Fertility in New York, where the women were being treated, says that stress played a bigger part.

There unfortunately are some people that may never achieve a pregnancy Steve Spandon Centre for Reproductive Medicine and Fertility, New York

"I remember having patients of mine on TV asking where were their husbands or wives, where could they be located," he said.

Mr Spandon adds that some of his patients were firefighters. Even though they survived the attacks, they were affected by the death of more than 300 of their colleagues, he says.

"There unfortunately are some people that may never achieve a pregnancy, although obviously we hope for the opposite."

Pregnant women under extreme stress are more at risk of miscarriage - but these women were even more vulnerable.