Research led by University of Auckland Professor Chris Bullen and published this year showed that 23 per cent or women drank alcohol during the early stages of their pregnancies, while 13 per cent drank alcohol after their first trimester.
Several groups have been calling for mandatory warning labels, including Alcohol Healthwatch, the New Zealand Nurses' Organisation, and the Royal Australian and New Zealand College of Obstetricians and Gynaecologists.
But the alcohol industry has fought the move, saying the current voluntary regime is sufficient because most alcohol companies already used warning labels.
O'Connor said mandatory labelling will strengthen the Government's wider programme to change drinking behaviour among pregnant women.
"Hundreds of babies a year are born with Fetal Alcohol Spectrum Disorder because of exposure to alcohol in the womb. We need to take every action to reduce this harm."
Food Standards Australia New Zealand will develop the appropriate standard to bring it back to the forum for approval.
The forum noted the efforts of a large segment of the sector in voluntarily using pregnancy warning labels. It called for comprehensive consultation and a suitable transition timeline before the mandatory regime comes into effect.