New miscarriage warning over smoking
Women whose partners smoke heavily are at a greater risk of having a miscarriage, scientists have warned.
A study found that nearly a third of women whose partners smoked more than 20 cigarettes a day lost their babies within six weeks of conceiving, compared to one fifth whose partners did not smoke.
The dangers for a woman of smoking while pregnant are well known, but previous research into how male nicotine habits affect the pregnancy have been inconclusive.
The new study was conducted by researchers in the United States and China. The scientists now advise that both partners trying for a baby should kick the habit.
In the study, 526 newly-married women who did not drink or smoke were put into three groups, depending on whether their husbands smoked more than 20, less than 20 or no cigarettes each day.
The women, who were textile workers in China, were tested to detect early pregnancies - often before the women even knew they had conceived.
There was little difference in how likely the women were to conceive, regardless of their partners' smoking habits.
But almost a third of the women whose husbands smoked more than 20 cigarettes a day lost their baby within six weeks of becoming pregnant. By comparison, one fifth of the women whose husbands did not smoke miscarried early.
In all, 84 per cent of the women whose husbands did not smoke eventually fell pregnant and gave birth. Some 76 per cent of those whose husbands smoked heavily had successful pregnancies.
"The authors conclude that heavy paternal smoking increased the risk of early pregnancy loss through maternal and/or paternal exposure," said an article in the new edition of the American Journal of Epidemiology, where the research was published.
The study was conducted by the Harvard School of Public Health in America and Beijing Medical University in China between 1996 and 1998.
Dr Scott Venners, of the Department of Environmental Health at Harvard School of Public Health, said his study concluded that some of the babies lost by women whose partners smoked would otherwise have survived to full term.
Passive smoke exposure
The scientists believe that smoking could cause damage to the chromosomes in sperm. There is the added danger that a pregnant mother's exposure to passive smoke could also endanger the unborn child.
The researchers said: "In conclusion, this prospective study links heavy paternal smoking to increased risk of early pregnancy loss.
"It adds to an increasing body of literature on the adverse reproductive health effects of both maternal and paternal smoking and underscores the need to target public health interventions toward both maternal and paternal smoking to improve reproductive outcomes."