Drinking alcohol during pregnancy could harm not just a woman's unborn child, but her grandchildren and beyond.
Researchers in the US have found brain abnormalities linked to fetal alcohol spectrum disorder (FASD), at least in mice, can be passed down through the generations.
"Traditionally, prenatal ethanol exposure from maternal consumption of alcohol was thought to solely impact directly exposed offspring, the embryo or fetus in the womb," says Kelly Huffman from the University of California.
"However, we now have evidence that the effects of prenatal alcohol exposure could persist transgenerationally and negatively impact the next-generations of offspring who were never exposed to alcohol."
In the experiment, Prof Huffman's team found the children of mice with FASD also had reduced body weight and brain size, and were more likely to show signs of anxiety and depression. The defects were present in further generations.
"By demonstrating the strong transgenerational effects of prenatal ethanol exposure in a mouse model of FASD, we suggest that FASD may be a heritable condition in humans," says Prof Huffman.
Babies born with FASD often have intellectual and physical disabilities, behavioural problems and distinct facial features. It is irreversible. A study in 2015 found almost third of Kiwi women continue to drink alcohol during their first trimester, and 11 percent right up until birth.
The Ministry of Health says there is no known safe level of drinking, and recommends women abstain from alcohol from the time they decide to have a baby, through conception and the entire pregnancy.
The discovery that FASD affects children who were never exposed to alcohol is a clue to future potential therapies and perhaps even prevention, the researchers say.
The research was published in journal Cerebral Cortex.