Let's assume that you are a bartender. A woman walks into the bar who is obviously pregnant and orders a double vodka on the rocks. Can you refuse to serve her in order to protect her unborn baby?
If you were in New York City, you'd have to serve her or you'd risk being sued for discrimination. New York City recently adopted guidelines that explicitly state that the failure to serve alcohol to pregnant women is a violation of the City's Human Rights Law.
The New York City guidelines state that persons or entities subject to the law cannot use maternal or fetal safety as a pretext for discrimination or as a way to enforce traditional gender norms or stereotypes. Basically pregnant woman cannot be treated differently than non-pregnant women or men. That kind of makes sense. This situation is no different than a school who refuses to accept Muslim students for their own protection, or some other nonsense reason like that.
Illinois has a similar law that prohibits discrimination against any individual because of his or her race, color, religion, sex, national origin, ancestry, age, physical or mental disability, sexual orientation, or pregnancy.
Based on the language of the Illinois Human Rights Act, it is quite possible that a pregnant woman could file a lawsuit in Illinois if she was denied service simply because of her pregnancy. She might not be the most popular plaintiff in the courthouse, and I doubt a jury would award her very much money, but she could file a lawsuit nonetheless. Cheers!