For years doctors and scientists have warned that smoking is bad for our health. For pregnant women, the potential health risks extend to the unborn child. Known risks for babies of women who smoke while they are pregnant include the possibility of birth defects, miscarriage, or premature delivery. A recent study published in Human Reproduction Update provides more specific information on both the types and the severity of birth defects that are likely caused by smoking.
Although science has made general statements about birth defects caused by smoking for many years, researchers at University College London set out to determine more specifically which birth defects can be attributed to smoking while pregnant. The research team pulled information from 172 research papers accumulated over 50 years. The study included over 174,000 cases where babies were born malformed as well as 11.7 million children born without birth defects. They concluded that smoking increased the risk for babies to be born with these defects:
• Eyes: Babies born to women who smoked had a 25 percent higher risk of eye defects.
• Limbs: The risk of a baby having missing or deformed arms or legs was 26 percent higher for women who smoked.
• Gastrointestinal defects : Babies had a 27 percent higher risk of stomach and intestinal problems.
• Clubfoot: The risk of a baby having a clubfoot was 28 percent higher.
• Cleft lip or palate : Babies were at 28 percent higher risk of having a cleft lip or palate if mom smoked while pregnant.
• Skull: The risk of skull defects was 33 percent higher for babies born to women who smoked.
• Gastroschisis: The risk was 50 percent higher that a baby would be born with part of the stomach or intestine outside the abdomen or protruding through the skin.
Ongoing campaigns from the healthcare community have brought about declines in smoking in recent years. However studies show that the decline in smoking among high school girls has dropped off. Between 1999 and 2003, cigarette smoking decreased in this group by 37 percent. However from 2003 to 2007, the decrease in smoking among high school girls was only 2.3 percent.
Similarly, despite clear evidence that smoking while pregnant can harm the unborn child, 20 percent of pregnant women in the United States continue to smoke while pregnant. That is compared to only 9 percent among pregnant women over the age of 35. Statistics from the UK show that 45 percent of pregnant women under 20 and 17 percent of all pregnant women still smoke while pregnant.
According to the University College London research team, birth defects have rarely been mentioned in connection with the risks of smoking for pregnant women because scientists were not able to pinpoint which defects were linked to prenatal smoking. Thanks to this study, researchers and healthcare providers can now be much more specific when explaining the risks to pregnant women who smoke.
Lead author Professor Allan Hackshaw, UCL Cancer Institute and member of the Royal College of Physicians Tobacco Advisory Group, said, “The message from this research is that women should quit smoking before becoming pregnant, or very early on, to reduce the chance of having a baby with a serious and lifelong physical defect."
Science Daily. Deformed Limbs One of Several birth Defects linked to Smoking in Pregnancy. Web. August 22, 2011.
American Lung Association. Women and Tobacco Use. Web. August 22, 2011.
Centers for Disease Control. Fact Sheet – Adult Cigarette Smoking in the United States - Smoking & Tobacco Use. Web. August 22, 2011.
Reviewed on August 23, 2011
by Maryann Gromisch
Edited by Jody Smith