Research from The University of Queensland suggests even small amounts of alcohol consumed during pregnancy could cause insulin-resistance in male rat offspring.
The study mimicked 'special occasion drinking', such as a family barbeque or birthday party, where a pregnant woman might be encouraged to have one or two alcoholic drinks.
UQ scientist Dr Lisa Akison said male rats exposed to this low level of prenatal alcohol showed signs of becoming diabetic at around six months old.
"We only gave alcohol to the mother rats on two days during their pregnancy", Dr Akison said.
"Their blood alcohol concentration only reached 0.05 per cent, and yet their male offspring recorded higher than normal insulin levels."
Dr Akison said it was interesting to discover such insulin-resistance was sex-specific, occurring only in the male rats.
"There are a couple of potential reasons for this, one being that during pregnancy, the placenta adapts to a prenatal stress differently depending on if it's a male or female fetus, and this can have an impact on fetal growth and development," she said.
"The other factor is hormone changes as offspring grow into adulthood.
"In this case, we know that oestrogen protects against insulin-resistance, and because males don't have high oestrogen, they don't experience the same protection."
Dr Akison said while the research was in its early stages, it did raise questions about the safety of alcohol during pregnancy.
"More research is needed to establish any definitive link between alcohol and insulin resistance in humans.
"But this study does suggest that even a small amount of alcohol during pregnancy could be harmful, so if you're planning on getting pregnant it might be wise not to drink," she said.
"Families, partners and friends should support a woman's choice not to drink alcohol during pregnancy.
"If a woman unknowingly drinks alcohol during the early stages of pregnancy, the important thing is to stop once they realise they're pregnant, have a good diet and take care of themselves for the remainder of the pregnancy for the optimal health of their child."
This research is published in The Journal of Physiology (DOI: 10.1113/JP278531).