Research published by scientists at the US University of Rochester Medical Centre in the Journal of Tobacco Control reveals that women exposed to second-hand smoke as children or young adults have an increased likelihood of experiencing miscarriages or trouble conceiving.

The research team studied 4,800 women treated at the Roswell Park Cancer Institute in New York, who were asked to give details of their pregnancies, miscarriages, smoking history and whether they were exposed to second-hand smoke at any points in their lives. The team found that those exposed to send-hand smoke for six or more hours per day in the past had a 68 per cent increased chance of miscarriage or experiencing problems getting pregnant, as compared to women who had never been exposed to second-hand smoke.

Luke J Peppone, a research assistant at the James P Wilmot Cancer Centre at Rochester, commented: 'we all know that cigarettes and second-hand smoke are dangerous, breathing the smoke has lasting effects, especially for women when they're ready for children'.

Four out of five women taking part in the study had been exposed to second-hand smoke at some point in their lives, and half grew up in a home with smoking parents. Of those women whose parents were smokers, the study found they were 26 per cent more likely to have difficulty conceiving and 39 per cent more likely to have miscarried. Peppone called the results 'breathtaking', and stated that the study, 'certainly points to yet anther danger of second-hand smoke exposure'.

Scientists believe that second-hand smoke causes changes in hormonal action relating to fertility and pregnancy and that it can affect the cervix. In the past links have been found between smoking and sudden infant death syndrome, miscarriage and birth defects. Despite the warnings, an estimated 15 per cent of mothers continue to smoke during pregnancy, and approximately 43 million US women are exposed to others' smoke.