The safest approach in pregnancy is to choose not to drink at all, according to the first all-island guide aimed at answering women's questions on the issue.
The guide says it is "important to be aware that when you drink alcohol, your baby also drinks. The risk of damage to your baby's physical and mental development increases the more you drink, and binge drinking is especially harmful".
It comes after a recent study found that one-in-three women surveyed admitted binge drinking in the first 15 weeks of pregnancy.
The guide has been produced as a result of collaboration between the HSE, the Public Health Agency in Northern Ireland and the Western and Southern Health and Social Care Trusts.
It points out that "most women are aware of Foetal Alcohol Syndrome (FAS) – where children have growth problems, facial defects and lifelong learning and behaviour problems".
Another risk is Foetal Alcohol Spectrum Disorders (FASD), which describes the range of less obvious effects or "sleeping symptoms".
These include being born small, having problems eating, sleeping, seeing and hearing.
Dr Nazih Eldin, head of health promotion in the HSE Dublin North East, said: "It is important that every future parent knows they can give their child complete protection against alcohol-related harm simply by avoiding alcohol in pregnancy. The message isn't just for pregnant women.
"Partners and friends also need to understand the risks to the unborn child and provide support and encouragement to women during an alcohol-free pregnancy."
The Alcohol and Pregnancy Guide can be downloaded at www.hse.ie