Is it okay to drink while pregnant?

Generally not. Fetal alcohol syndrome (fas) , which can cause growth problems, facial abnormalities and central nervous system issues in the newborn, is the result of maternal alcohol consumption during pregnancy. It is quite likely that FAS will only result from heavy and repeated drinking, but there is no certainty in that regard so all groups recommend against any alcohol from conception to birth.
No. Alcohol can damage a baby's brain causing cognitive, learning, emotional and behavior problems. We don't know how much alcohol it takes so no amount of alcohol should be assumed to be safe. Drinking too much on just a few occasions can cause fetal alcohol syndrome (fas) or alcohol related neurodevelopmental disorder (arnd) even if you don't drink at all during the rest of the pregnancy!