Drinking too much alcohol during pregnancy can cause permanent damage to unborn child, say researchers.
The new study conducted using mouse model suggests this may be because alcohol chemically alters the foetus's DNA, affecting how genes are expressed.
To find whether a mother's alcohol consumption might affect the way her child's genes are expressed, lead researcher Suyinn Chong, from Queensland Institute of Medical Research in Herston studied mice with genes for brown and yellow fur that are known to be modified by environmentally induced epigenetic changes.
"It's a good model to use because you can tell whether a mouse's environment is affecting the expression of its genes just by looking at its coat colour," New Scientist magazine quoted Chong as saying.
Females with two copies of the gene for yellow fur were mated with males that had two copies of the brown fur gene.
The expectant mice were given alcohol during the first half of pregnancy.
When the team looked at the newborn mice, they counted twice as many brown mice as they expected.
"This means that the alcohol was affecting the epigenome of the mice - controlling whether their genes were switched on or off," Chong added.
In the second study, researchers studied the DNA in the mice's liver cells.
They found 15 genes that had been altered to either increase or decrease their activity in mice whose mums drank during pregnancy.
Infant mice that had been exposed to alcohol in the womb also showed some symptoms of human fetal alcohol syndrome, such as a lower body weight and smaller skulls.
This shows that if women drink too much in pregnancy, epigenetic changes may cause some of the permanent symptoms seen in fetal alcohol syndrome in their children.
"This is an important development in understanding how alcohol exposure in the uterus causes lifelong detrimental effects in the offspring," said Michele Ramsay, a geneticist at the University of the Witwatersrand in Johannesburg, South Africa.
If the study confirms that fetal alcohol syndrome causes epigenetic changes in humans too, it might help in early detection of the syndrome.
The study appears in journal PLoS Genetics.