Whole grains have a lot about them that are better than refined grains, and sprouted is even better, but decreasing or skipping grains is even better still. Greens, root veggies, and fruits are such better sources of good carbs and nutrients, and more texture and flavor. Those anti-nutrients mentioned by the previous poster make you need extra minerals in your diet to make up for them. It's how plants fight back against their attackers, they produce basically mild poisons. They can cause a lot of inflammation, like body aches, bloating, digestive issues, for some people headaches and rashes. We get used to it but if you try going off it a long time you'd be surprised how great you feel.
At the same time, if you're nauseated or having food aversions it's hard to eat anything that's not bland and starchy sometimes, at some points in pregnancy it's easiest to eat anything that you can manage to eat no matter the specific health factors. Potatoes and white rice are what they call the "safe starches", the drawbacks are milder with those.