Smoking during pregnancy may result in behavioral issues in children, a new study published in the Journal of the American Medical Association found.
Led by the University of Leicester's Dr. Gordon Harold, the scientists pulled together data from three studies done in New Zealand, the UK and the United States in which women were asked whether or not they smoked cigarettes while pregnant.
The studies also included a report on their children's behavior between the age of four and 10, including whether or not they got into fights or had a difficult time paying attention in school. A number was then assigned to each child, with higher scores indicating more issues in regards to conduct.
Furthermore, in attempt to rule out another important factor -- parenting style -- the researchers compared children who were raised by adoptive parents versus their own.
What the researchers found was that among women who raised their biological children, those who didn't smoke during pregnancy scored around 99 while those who smoked 10 or more cigarettes a day scored an average of 104.
Such a difference, Harold told Reuters, would be noticeable in daily life.
Moreover, similar results were observed for children raised by adoptive parents once their birth mothers were interviewed regarding their own smoking habits.
The reason behind this, said Darya Gaysina, another researcher from the University of Leicester, though not clear, "may include genetic factors and other prenatal environmental hazards, including smoking itself," she and her colleagues hypothesize, according to Health Day.
Still, Harold told Medscape Medical News, the findings "highlight the importance of considering factors that influence children both prior to birth as well as following birth in understanding the developmental origins of conduct problems -- a set of problems recognized as affecting a rising proportion of youth (boys and girls aged 5 to 15) both nationally and internationally."