Smoking ruins breast milk

Equivalent of 20 cigarettes can be passed on to infants

Ruth Dunley The Ottawa Citizen

Smoking mothers who breastfeed can pass on the equivalent of 20 cigarettes a day to their babies, a new study suggests.

"It has not been shown before that nicotine is transferred to infants in breast milk," said Dr. Peter Macklem, scientific director of the INSPIRAPLEX respiratory health network, whose members released the study. The network links 70 respiratory health researchers in 18 universities and research centres across Canada.

Researchers tested the urine of two-week-old infants for levels of cotinine, the form of nicotine when it is broken down in the body. Extremely high levels of cotinine were found in infants that were breastfed by mothers who also smoke.

"The levels are so high in the infants' urine, it is almost as high as an adult who smokes nearly 20 cigarettes a day, which is really quite frightening," said Dr. Moira Chan-Yeung, the principal researcher in the study.

While there have been studies that have discussed the negative effects of smoking while pregnant and of the dangers of exposure to second-hand smoke, researchers have never made a link between breastfeeding and smoking, Dr. Chan-Yeung said.

"A lot of mothers, when they are pregnant, they try very hard to give up smoking," she said. "And when the pregnancy is over, they take up smoking again."

Dr. Chan-Yeung said a mother did not need to be a heavy smoker to pass on high levels of nicotine to her baby since cotinine appeared to be concentrated in breast milk. In fact, breastmilk contained levels of cotinine three-times higher than that found in the mother's bloodstream. She fears the study might prompt some women to stop breastfeeding, rather than quit smoking. "I think it is a major concern ..." she said.

Dr. Allan Becker, the other principal investigator in the study, said its main message is that "smoking is bad, breastfeeding is good -- don't combine the two." He said mothers need to understand the potential risks of resuming smoking after a pregnancy.

"What they need to realize is that they have the potential for not only causing increased chest problems, increased allergies, increased asthma and increased respiratory disease, but they also have the increased risk that they are going to hook their child," said Dr. Becker. "They're going to, in fact, create a child that is predetermined to be addicted to cigarettes and smoking."

Dr. Becker pointed to another recent study that discovered children exposed to second-hand smoke in the home are more likely to take up smoking.

In this study, researchers measured cotinine levels in the saliva of 201 elementary school children to assess the levels of second-hand smoke they were exposed to at home. They were studied again in adolescence.

By the time of the second examination, 83 of the 201 children identified themselves as smokers, meaning they had at least one cigarette a week for a month or more.

"Our concern is that (mothers are) condemning two people to ongoing addiction -- themselves and their infant child," said Dr. Becker. "They need to realize that exposure to tobacco smoke, whether it's inhaled, and especially if it's ingested, is a big risk for that subsequent addiction."