Newborns may run the risk of having congenital heart defects if their mothers, when they were pregnant, were smoking, says a new study. The more a pregnant mother smokes, the higher is the risk for the newborn to acquire the heart condition.
The study, titled Risk of Congenital Heart Defects in the Offspring of Mothers Who Smoke Cigarettes During Pregnancy, was presented at the annual meeting of Pediatric Academic Societies (PAS) in British Columbia, Canada on May 3.
"...Usually, the cause of a heart defect is unknown. I saw this research as an opportunity to study what might be a preventable cause of congenital heart defects," Dr. Patrick M. Sullivan, lead author of the study, said in a statement. He is also a master's student in epidemiology at the University of Washington School of Public Health and a clinical fellow in pediatric cardiology at the Seattle Children's Hospital.
To establish the link between maternal smoking in the first trimester of pregnancy and heart defects, study authors used hospital discharge records and birth certificate data from the Washington state and identified that 14,128 children were born with various heart defects from the years 1989 to 2011. Said recorded cases were matched to 62,374 children born during the same year but without heart defects.
Subsequently, the study authors made a comparison of the percentage of children with heart defects and whose mothers smoked during pregnancy to the percentage of children with no heart defects and whose mothers reportedly smoked during pregnancy. Data on the status and frequency of smoking of these pregnant women were included in their birth certificates.
The results of the study show that when pregnant mothers smoked, it is more likely for their newborns to have heart defects than not have one, and that the risk was found to be highest in heavy smokers. Around 50 to 70 percent higher risk were discovered for newborns to have anomalies of the vessels and valve carrying blood to the lungs and around 20 percent higher risk for newborns to have holes in the body's wall that separates two collecting chambers of the heart. Unfortunately, all these defects often demand invasive procedures to correct it.
Study also indicates that older pregnant women who smoked were found to have higher risk of bearing a child with heart defects than the younger mothers who smoked. Nevertheless, study says that women of 35 years old and over are less likely to smoke when they're pregnant. Maternal smoking in the first trimester is estimated to account for one to two percent of heart defects.
Regardless of the efforts of public health professionals to minimize smoking, Dr. Sullivan discloses that women, the younger ones in particular, still smoke during pregnancy.
"Ongoing cigarette use during pregnancy is a serious problem that increases the risk of many adverse outcomes in newborns. Our research provides strong support for the hypothesis that smoking while pregnant increases the risk of specific heart defects," he says.
Other than heart defects, cigarette smoking for pregnant women runs the risk of many other birth defects for the newborns, such as missing or deformed limbs and cleft lips or palates.
This recent study somehow supports another study, Passive smoking and children, which was published [pdf] in 2010 and conducted by the Tobacco Advisory Group of the Royal College of Physicians. The previous study shows that there's 15 percent increased risk for newborn to have a heart defect due to pregnant mothers who smoked.
"This study provides further evidence of the potentially long-term damaging effects of smoking during pregnancy. All pregnant women who smoke should be offered advice and support to quit to avoid life-threatening conditions to both themselves and their babies," said Amanda Sandford, who is research manager of the Action on Smoking and Health (ASH) organization.
Research says the British government is targeting to minimize the ratio of pregnant women who smoke, from 14 percent down to 11 percent in year 2015. At present, it is estimated at 13 percent, which is parallel to 83,000 babies who are born each year to smoking mothers in England.