Dangers of Smoking During Pregnancy

By Margarita Nahapetyan

Australia's New South Wales Cancer Institute in its study has come to the conclusion that pregnant women who smoke greatly increase the risk their child will develop a life-threatening cancer, such as leukemia (cancer of the blood or bone marrow). Although smoking during pregnancy has long been known to be dangerous for babies causing birth complications, scientists have never before directly linked it with cancer. Babies born to smoking mothers were up to five times more likely to get cancer than those born to non-smokers. Scientists have provided the strongest evidence that smoking during pregnancy also leads to premature birth, low birth weight and newborn's hospitalization to a neonatal intensive care unit (ICU). More than a million birth records have been assessed from 1994 to 2005 across NSW and it was established that in 948 cases the growing baby developed a cancer.

According to the study babies born with a low birth weight, the most common smoking-pregnancy complication, have 1.7 times the risk of developing leukemia. Likewise, it increases the risk of developing cancer of the brain or central nervous system by 1.8 times. Newborns who, required immediate ICU care are at most risk - they are 2.7 times more likely to be subsequently diagnosed with cancer, and 3.7 times more likely to develop cancer of the central nervous system and brain cancers, 4 times more likely to develop eye cancer, and kidney cancer risk was 5 times higher, as opposed to children born to mothers who did not smoke during pregnancy.

Professor Jim Bishop, chief executive of the of the New South Wales Cancer Institute said it was the first time that a connection between childhood complications such as premature birth and the risk of cancer had been shown. "We've not yet made the direct link between pregnancy and smoking and those poor outcomes leading to childhood cancers, but it's clear that we can do something about those complications and that is not to smoke during pregnancy," he advised. "Everybody knows that smoking causes cancer, stroke, heart disease and emphysema but all mothers and mums-to-be should also understand the potential damage to a child caused by prenatal smoking," said Minister for Medical Research, Jodi McKay, and emphasized that the number of Australian women who smoked during their pregnancy was "alarming". 17 % of Australian women admitted that they smoked during pregnancy. Pregnant women often think that smoking will just result in a lower birth weight but they probably don't know that it is also linked to reduced lung function and rates of asthma.

The research, by the Cancer Institute of NSW, was presented at an international conference late last year.

According to Canadian researches smoking pregnancy leads to aggressiveness in children. The behavior of about 2000 children aged between 18 months and 3 years has been examined and it was found that women who smoked during their pregnancy were more likely to have aggressive children than non-smoking women. Kicking, hitting, biting, bullying and fighting were taken as factors of aggressiveness. Besides, the researchers specified other factors associated with aggressive behavior in children - smoking mothers under the age of 21, smoking mothers with a low income and smoking mothers who themselves had a history of antisocial and aggressive behavior. . "Mothers-to-be whose lives have been marked by antisocial behavior have a 67% chance to have a physically aggressive child if they smoke 10 cigarettes a day while pregnant, compared with 16% for those who are non-smokers or who smoke fewer than 10 cigarettes a day. Smoking also seems to be an aggravating factor, although less pronounced, in mothers whose antisocial behavior is negligible or zero," said Prof Jean Seguin of the Université de Montréal, co-author of the study. Among smokers with a low income, heavy smokers had about 40 percent chance of having very aggressive children, compared with 25 percent of other mothers who were moderate in their smoking habits or did not smoke at all. With a higher income, the difference between heavy smokers and non or moderate smokers was just 8 percent. Other factors of aggressiveness in children were also taken into account, factors like divorce and depression during pregnancy, but the effect of smoking on aggression still remained highly significant.

The study was published in the 'Development and Psychopathology' journal.