Passage one

A simple test that detects nicotine levels in urine has helped pregnant women in Birmingham to cut down on cigarettes and in some cases to kick the habit altogether. The test turns urine pink in the presence of nicotine and its breakdown products. "It is very important that the patient is right there to see it," says Graham Cope, a research fellow at the Wolfson Applied Technology Laboratory at the University of Birmingham, who developed the test.

A recent survey by the baby's charity Tommy's Campaign found that a quarter of pregnant women in Britain smoke throughout their pregnancy. But most of the information doctors get about their patients' smoking habits is self-reported. "Smokers tend to underestimate their consumption," says Cope. Even if a smoker owns up, it is hard to know how much nicotine they are actually consuming; different brands of cigarette have different nicotine levels, and styles of inhaling vary.

Cope's device provides the first quick biochemical measure of tobacco absorption. Thiobarbituric acid and other chemicals react with nicotine and its by-products, such as cotinine, to produce the pink color. The more tobacco the smoker has consumed, the pinker it gets. Researchers then use a standard colorimeter to measure the depth of color in order to quantify consumption. In all, the procedure takes five minutes.

Cope is just completing a pilot study in which he has screened 1 000 pregnant women in Birmingham. Half of them were tested and shown the results on their first visit. They were screened at least once more, towards the end of their pregnancy. The others were screened but were not given the results.

Of the 500 women who were shown their results, just over 100 were smokers. During their pregnancy, 20 percent of them quit, while another 30 percent significantly reduced the amount they smoked. Even among the 50 percent of smokers who said they had not changed their habits, the test showed that about half had in fact cut down. "They were more aware of their habit," says Cope.

In contrast, only about 7 percent of the women in the control group managed to quit. Very few cut down, and 45 percent actually increased the amount they smoked. This compares badly to the results in the test group, where only 15 percent smoked more.