Heavy use of common painkillers during late pregnancy doubles the risk of wheezing in young children, UK researchers have found.
Children born to mothers who frequently used paracetamol after 20 weeks of pregnancy were more than twice as likely to suffer from wheezing, according to the study of 9000 pregnant women.
鈥淥ur findings are interesting because it is another clue that the environment before birth is important in determining asthma,鈥� says Seif Shaheen at King鈥檚 College, London, UK.
Advertisement
But he adds: 鈥淔requent use of paracetamol during early pregnancy and moderate use throughout pregnancy did not increase the risk of wheezing. So if painkillers are needed, pregnant women should still take paracetamol 鈥� but not use the drug every day.鈥�
Breakdown product
The women were asked about their paracetamol use when they were 18 to 20 weeks pregnant and again at 32 weeks of pregnancy. Six months after giving birth, the mothers were asked about symptoms of wheeze in their children, and then again every year.
One percent of the women studied used paracetamol heavily 鈥� most days or daily 鈥� after 20 weeks of pregnancy and this was associated with a doubling in the risk of wheezing in children at two-and-a-half and three-and-a-half years old. The researchers discounted 20 other possible factors, including maternal asthma, smoking and per ownership.
鈥淲e know that paracetamol can cross the placental wall into the baby鈥檚 blood stream and that one of the breakdown products of paracetamol is a toxin that binds to cell proteins. We suspect it damages the lining of the lungs in the fetus,鈥� Shaheen told New 杏吧原创.
The body normally produces an antioxidant response to the toxin, called glutathione. But Shaheen thinks these levels may not be high enough in the developing fetus to protect its lungs.
Hereditary factors
About 20 per cent of all children wheeze in their first two years, but only a third of those go on to develop asthma.
鈥淚t has been shown that smoking during pregnancy is one of the strongest causal effects for wheezing in children, so it is not unexpected that the prenatal environment is important,鈥� says Hasan Arshad from David Hide Asthma and Allergy Research Centre on the Isle of Wight, UK.
But Arshad thinks that the prenatal environment is more likely to be important for wheezing children who do not go on to develop asthma. Hereditary factors are thought to be involved in children who do develop asthma, he says.
Journal reference: Thorax, (vol 57, p 958)