http://www.health.harvard.edu/blog/study-no-connection-between-drinking-alcohol-early-in-pregnancy-and-birth-problems-201309106667. Risk for Fetal Alcohol Syndrome increases with heavy drinking, which is more than one drink a day.
American women used to drink moderately during pregnancy as a matter of course before American society swung heavily towards our current beliefs that children are precious and fetuses matter more than the humans who carry them. In the 60's and 70's babies and children were regularly vilified in American mainstream media from movies like Rosemary's Baby (1968) to The Brood (1979). I believe the current angelification (I made up that word) of kids is temporary and in another generation or two we'll be back to a more reasonable view of how much adults should sacrifice for children.
So if you're pregnant and you want a drink, have a damn drink. And if you see a pregnant woman enjoying a glass of wine or shot of tequila, leave her alone!