Full impact of pregnancy smoking on kids revealed

Smoking during pregnancy has been found to cause behavioural problems in children — even many years later — an Irish study has found.

Latest research from the Growing Up in Ireland study found that 13% of mothers smoked all the way through their pregnancy.

Also, being poor and having low levels of education contribute to the risk of smoking during pregnancy.

Co-author Richard Layte from Trinity College Dublin, said they had conducted studies with older children to see how their physical and mental development was affected.

“What we found was that those children whose mothers smoked during pregnancy were more likely to exhibit abnormal patterns of behaviour, such as conduct or hyperactive disorder,” said Prof Layte.

“We were more likely to see those behaviours at age nine and we know that those behaviours have an impact on their educational development.”

The children, who were nine years old at the start of the study in 2007, were now approaching age 17.

Prof Layte said there was good evidence in scientific literature of a “mechanism” linking maternal smoking to a child’s development and then to their subsequent behaviours.

“That is a really important pathway that we have got evidence of in Ireland and we suggest that there are both physical, emotional and mental consequences of maternal smoking. As the children get older, we are looking at the way those early exposures shape both their physical and emotional health.”

The Government-funded study follows the progress of almost 20,000 children and their families first visited in 2007/08.

There are 11,134 children participating at nine months, three years and five years of age, and 8,568 interviewed at nine years and 13 years of age.

The latest study made comparisons with children born in 1999 and 2007 and found the proportion of women smoking at all in pregnancy had fallen from 28% to 17%. However, if the woman’s partner continued to smoke during the pregnancy, the mother was 70% less likely to quit.

“If we are going to counsel women about their smoking during their pregnancy, we are going to have to counsel their male partners too.”

Smoking was strongly related to the women’s mental health. Women experiencing a great deal of stress were 37% more likely to smoke.

Prof Layte said those women needed special help.

Ireland is about mid-table in an international context for mothers smoking during the third trimester of pregnancy at almost 15%.

Sweden has the lowest proportion of such mothers at just under 5%, but Scotland, at almost 20%, or one in five, has the highest.

Smoking over 11 cigarettes a day decreases birth weight by a third of a kilo on average. Children who are passive smokers are more at risk of acute as well as long-term chronic illnesses as adults.

Almost half of children were weaned onto solid foods before the guideline age of six month, suggesting parents are unaware of the health consequences.

Less breastfeeding and early weaning onto solid foods is associated with an unhealthy pattern of weight gain in infancy.