During pregnancy is drinking apple juice, water, and milk a good thing for the baby?

Sure! All these beverages are a good idea in moderation. They help maintain hydration and avoid preterm labor and oligohydramnios. Talk to your obstetrician if you have diabetes mellitus to make sure you are not violating your caloric restrictions. Just make sure you only drink pasteurized products!
Not relevant . There is no reason to increase consumption of these two drinks. Just eat a healthy balanced diet. Milk and juice can be a part of that. They also have a lot of calories and can lead to weight gain.