Tuesday, May 18, 2004

Olympian fears

It seems like fear drives the Olympics these days as much as 'citius, altius, fortius'. The Greeks are, apparently, spending up to €1 billion on security for the Athens games. And fear of a screwed-up planet seems to be a major factor behind bid criteria for future games. For example, Sydney made a major play of reclaiming land affected by toxic waste. I'm sure London will too.

But what about just organising a decent event?

BBC NEWS | Science/Nature | Olympic bid cities going for green

Passive smoking and pregnancy

Does second-hand smoke increase the risk of miscarriage?

Researchers in the USA and China claim to have discovered a link between passive smoking and miscarriage. Their report, published in the American Journal of Epidemiology, suggests that the chance of early pregnancy miscarriage for women married to heavy smokers is significantly greater than for women married to non-smokers. The researchers believe that smoking may affect both the quality of the husband’s sperm and the balance of hormones in the woman’s body. Professor Alison Murdoch, president of the British Fertility Society, told BBC News: ‘Everyone in a household where there is going to be a baby should stop smoking.’

There are some problems with this study. The first is that many pregnancies end early, often before women are even aware that they are pregnant. This study merely suggests it is a matter of degree: women with non-smoking husbands suffered pregnancy loss in 30 per cent of cases; for women with husbands who were moderate smokers the figure was 32 per cent, and for women with heavy smoking husbands it was 41 per cent. However, the numbers for the heavy smokers were skewed by a very small number of women (five) who suffered pregnancy losses on three occasions during the course of the study.

The study made no attempt to measure how much actual exposure women had to smoke. The only measure was the husband’s statement of smoking habits at the start of the study – so whether the husband’s smoking levels increased, decreased or stayed the same during the study is unknown. Nor do we know how often these husbands smoked in the company of their wives.

The biggest problem with the study is the naive acceptance that all these non-smoking women really are non-smokers. The report notes that in China 70 per cent of men say they smoke, compared with only four per cent of women. Clearly smoking must be rather unfashionable, or possibly frowned-upon, for Chinese women. It is hard to believe that at least some of these women do not light up from time to time; and the wives of heavy smokers may be more likely to smoke on the sly than those whose husbands do not smoke at all.

This tendency among some pregnant women to avoid admitting that they smoke can be glimpsed in a new initiative in Glasgow (see Parental rights up in smoke), which will test pregnant women who claim to be non-smokers as it is known that some do not disclose their smoking habits to health workers. Is China really so different?

The authors of the report admit that ‘results of investigations of increased risk due to maternal exposure to passive smoke have been inconsistent’. The study does not offer much clarification on the subject of passive smoking and pregnancy. But you would never guess that there was such weak evidence from the bald comments made by some health campaigners.

Paternal smoking and pregnancy loss, American Journal of Epidemiology, 2004; 159:993-1001

Passive smoke link to miscarriage, BBC News, 12 May 2004

First published on spiked's Don't Panic page.