There is always more to be said, but there is a lot of discussion on this issue in the past questions:
Was Fetal Alcohol Syndrome extremely common in the pre-modern era? (/u/Noble_Devil_Boruta and /u/SpicyBaconator
Back in the middle ages drinking beer and wine was a common thing to do on a regular basis and since I can't imagine, that the dangers of alcohol consumption for pregnant women was known yet, how come that most babies born weren't affected by fetal alcohol syndrome? (/u/rocketsocks)