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Infertile sons for smoking mums-to-be

Mothers who smoke early in pregnancy may be risking infertility in their unborn sons by arresting the development of sperm cells, new research suggests.

Scientists found numbers of immature reproductive cells were dramatically reduced in male embryos exposed to the effects of tobacco.

The findings echo those of previous research showing a similar effect on female embryos.

They were published alongside the results of a second study explaining why men who smoke may be putting their fertility at risk.

The new work sheds further light on the links between smoking and infertility, and reinforces public health advice urging couples to quit the habit before attempting to conceive.

The first team led by Professor Claus Andersen, from Denmark, looked at 24 embryonic testes obtained from legally terminated pregnancies.

Each of the aborted male embryos was between 37 and 68 days old.


The scientists compared the number of germ cells -- immature cells that become sperm in males and eggs in females -- in the testes of embryos from smoking and non-smoking women.

Those from smokers contained less than half as many germ cells as those from non-smokers.

The number of non-reproductive somatic cells was also reduced by more than a third in the testes of embryos from smoking mothers.

The effect was dose dependent, so that the more a woman smoked the more impact it had on the embryo.

Overall, the number of germ cells in male and female embryos exposed to tobacco smoke were reduced by 41pc.

Prof Andersen said: "As the germ cells in embryos eventually develop to form sperm in males and eggs in females, it is possible the negative effect on the numbers of germ cells caused by maternal smoking during pregnancy may influence the future fertility of offspring."

The findings may help to explain the trend towards reduced fertility seen in recent years, said Prof Andersen.