MEN with semen of 'marginal' quality could improve their chances of conception by giving up smoking, say researchers from the University of North Carolina. In an analysis of 20 studies, published in Fertility and Sterility, they found smokers' sperm density to be 13 to 17 per cent lower.

Researchers at Duke University School of Medicine, Durham NC, write in the Journal of the American Medical Association that a mother-to-be who smokes may do her foetus more harm than if she took cocaine. Both habits restrict blood flow to the unborn child, but nicotine may also have a harmful effect on brain cell development in the third trimester.