There are many problems with this.
I want you to think of the logic: You can kill your unborn child up to 24 weeks, but you can't drink alcohol.
We don't know the "safe" level of alcohol, and we don't know the danger threshold.
If you are going to criminalize an act, the parameters have to be fair and clear.
Would drinking Communion wine violate the ban?
What if there are other factors contributing to mental retardation? If women are binge-drinking while pregnant, chances are the rest of their lifestyle isn't exactly healthy, either.
And what about women who experience cryptic pregnancies?
And where do you draw the line on legal products?
Until we know how much alcohol is safe and unsafe, I think the only line of demarcation you can draw is whether the product is legal or not.