Mothers warned drinking during seventh to 12th week of pregnancy puts unborn babies at highest risk of foetal alcohol syndrome
Pregnant women who drink alcohol were found to have an increased risk of having children with FASD – a series of preventable birth defects
Drinking regularly during pregnancy is known to increase the odds of having children with foetal alcohol syndrome.
However, scientists have now found that the risk to a woman's baby is highest if they consume alcohol in the seventh to 12th week.
A team led by Haruna Sawada Feldman from the University of California, San Diego, studied nearly 1,000 women during their pregnancies over three decades.
They found that drinking during the second half of their first trimester was linked with growth deficiencies in weight and height along with facial deformities that are telltale signs of foetal alcohol syndrome disorders (FASD).
For each extra daily drink, a woman’s baby was 25 per cent more likely to have an abnormally shaped lip, 12 per cent more likely to have a smaller-than-normal head and 16 per cent more likely to have low birth weight.
FASD are a series of preventable birth defects caused by alcohol that include, among others,
learning and attention disorders, vision and hearing defects, epilepsy and
Study co-author, Professor Philip May, from the University of North Carolina said: 'This paper clearly illustrates that
drinking alcohol, especially binge drinking, during the first seven to
12 weeks of gestation is associated with four of the most important
facial features characteristic of FAS as well as reductions in birth
length and weight that are also characteristic of infants and children
He added the results showed that there was no such thing as a 'safe' alcohol level during pregnancy, as the threshold for when unborn babies started to exhibit signs of the syndrome varied from woman to woman.
In the UK, women are advised not to drink at all during the first three months of pregnancy. The National Institute for Clinical Guidance said in 2008 advised that a small amount of alcohol one or two days a week after the first trimester is safe.
However, the guidance adds: 'There is uncertainty about how much alcohol is safe to drink in pregnancy, but at this low level there is no evidence of any harm to (the) unborn baby.'
The latest U.S study addressed two key challenges that face scientists studying the risk of FASD.
Firstly it questioned women during rather than after their pregnancy, so women were not affected by how their child had turned out. They also gave their answers to trained counsellors who guaranteed confidentiality.
Secondly, the alcohol-related features that indicates the start of a foetal disorder are often subtle.
So, as Feldman said: 'This study used an exposure-blinded expert dysmorphologist to look for these features.
'Furthermore, potential bias due to
subjectivity was reduced because these examinations were conducted in
the context of a larger study of more than 70 agents of interest, only
one of which was alcohol.'
Professor May said the data was extremely valuable, because: 'Research that links the quantity,
frequency and timing of alcohol consumption during pregnancy among
humans is virtually non-existent.'
The results will be published in the April 2012 issue of Alcoholism: Clinical & Experimental Research.