A "significant" link has been found between smoking and facial deformities in children, according to research.
An increased risk of cleft lip and palate was found
The study found that smoking in early pregnancy increased the risk of babies developing a facial cleft by up to three times.
The work was carried out by Professor Peter Mossey, from Dundee University's Dental School, who is leading a World Health Organisation project looking at the causes of cleft palates and lips across the globe.
Professor Mossey said the development of the palate takes place during a critical 48-hour period during the early stages of pregnancy at 6-8 weeks and can be disturbed by smoking.
He said: "Although there are other factors contributing, smoking appears to be a major risk factor for cleft palate in children.
"Often women don't know that they are pregnant at this early stage
and may still be smoking and binge drinking without realising that this could
have serious consequences for the baby developing in their womb.
"Although we know smoking is a major health risk, it is not generally known
that the effects of smoking can be passed down from mother to the developing child in such serious ways.
"I hope that these findings will enter the public consciousness and serve as
a further deterrent to smoking."
In the study comparing two groups of women in Scotland, Manchester and Liverpool, of the gorup whose children had a cleft lip and/or palate 42.1% smoked during the first trimester of pregnancy compared to 23.8% of the mothers who had children without clefts.
Nearly 70% of mothers in the 16 to 19 age group with cleft palate children were smokers.
The researchers also found that the more cigarettes smoked by the women per day, the greater the risk of giving birth to a child with a facial deformity.
Professor Mossey described the link between smoking and facial deformities as a "significant breakthrough" and said the initial research would now expand further by analysing data gathered from other countries.
Other factors being investigated are genetic predisposition to the condition and environmental factors such as nutrition, alcohol and passive smoking.
Figures from Cleft Services in Scotland - a network of clinicians who collect
data on incidences of the deformity - show that cleft lip and/or cleft palate
occurs in about one in 700 live births in Scotland.