The true scale of the damage that smoking is doing to our sexual and reproductive health became clear yesterday as doctors published a comprehensive report blaming cigarettes for the impotence of 120,000 young men, 1,200 cervical cancers, up to 5,000 miscarriages and for many couples' fertility problems.
Both partners should stop smoking before they attempt to conceive a child, says the report from the British Medical Association. It recommends that pregnant women should be entitled to stay off work with full pay if their employer cannot guarantee them protection from inhaling other people's cigarette smoke, which could harm their unborn child.
James Johnson, chairman of the BMA, said he found the results of the report "really quite shocking" for men, women and children. "Smoking appears to damage almost all aspects of sexual, reproductive and child health."
Between 14,000 and 19,000 babies were born with low birthweight because their parents smoked, he said, which meant that not only were they small, but they were likely to be sickly and have continuing health problems. The report also attributes up to 420 stillbirths and 260 deaths of babies under four weeks old to smoking and underlines the known link with cot death.
"It is quite clear from the litany of appalling effects that something has to be done," said Vivienne Nathanson, the BMA's head of science and ethics. She called for government policy on smoking to be more ambitious: the BMA wants to see legislation to ban smoking in enclosed public places.
Pregnant women have a legal right to protection from health risks in the workplace under European law, she said. "That has to include protection from people who smoke." Nine months of pregnancy should not have to be spent in purdah, she said. "We all have a duty to make the workplace and home and public places as safe as possible for pregnant women."
The report, Smoking and Reproductive Life, says studies show that smoking may cause impotence through damage to the blood circulatory system caused by exposure to the many toxins in cigarettes, including carbon monoxide. It estimates that 120,000 men aged between 30 and 50 in the UK are impotent because of the effects of smoking.
There is a small amount of evidence suggesting that passive smoking might also have an effect.
Smoking was recognised as a cause of cervical cancer - the biggest cause of cancer death in women worldwide - by the World Health Organisation in 2002.
Its main cause is infection with the human papilloma virus. Infection does not always progress to cancer, but the report says it is more likely to do so in smokers.
The report says that the message that smoking damages fertility is still not fully getting through. "Women are generally aware that they should not smoke while pregnant but the message needs to be far stronger. Men and women who think they might want children one day should bin cigarettes," said Dr Nathanson.
Women who smoke take longer to conceive than those who do not, and their chances of conceiving at all are reduced by between 10% and 40%. The more cigarettes she smokes, the longer it is likely to take a woman to get pregnant. She may not get pregnant at all - women are twice as likely to be infertile if they smoke.
Smoking also reduces the quality of semen. Not only do male smokers have a lower sperm count, but the sperm is more likely to be malformed, and byproducts of nicotine have been found to interfere with their motility, making it less likely that they will reach and fuse with the egg.
If a couple who smoke end up at the fertility clinic, their chances of successful test-tube treatment are reduced by their cigarette habit, says the report. One study showed that fertility treatment using ICSI - a technique in which a single sperm is injected into the egg - resulted in pregnancy for 38% of women whose partners were non-smokers, but only 22% of women whose partners smoked.
Smoking increases the chances that a pregnant woman will miscarry - by as much as 25%, according to the Royal College of Physicians. Babies born to smokers are on average 200-250g lighter than those of non-smokers. They are more likely to be ill and more likely to die in infancy. Smoking may increase the chances of malformations such as cleft lip and palate, the report says.
Inhaling other people's smoke during pregnancy can have ill effects on the baby, particularly if the woman works in a smoky atmosphere, such as a bar or restaurant. One study in the UK showed that the babies of women with the heaviest exposure to secondhand smoke were on average more than 70g lighter than the babies of those who were least exposed. Smoking can reduce the quantity and quality of milk produced by breastfeeding mothers.
The BMA says these findings, drawn together in the report from a large number of studies, are all the more worrying because while smoking is decreasing among most groups in society, it is going up among young women: 35% of women aged 20-24 smoke and girls and young women account for the majority of new smokers.
The government is considering giving councils the power to enact local bans but it is believed to favour education rather than enforcement.
Yet the report recommends that the government set more ambitious targets for reducing overall smoking rates and legislate for smoke-free public places. It should also ensure that employers are aware of their responsibilities to protect pregnant women from smoke and that employees understand their rights. More picture warnings should be used on cigarette packets, it says, and the promotion of cigarettes in films, sport, television and fashion "remains a grave concern".