The best diet isn't one that you should have to stick to. The best diet should come naturally. Make small changes in what you eat. Read ingredient labels and don't buy anything that contains something you have trouble pronouncing. Eat more real food, i.e., things you can identify by looking at them. Whole vegetables and fruits, whole cuts of meat, whole eggs, whole dairy. Calorie control is important too, but you'll be surprised at just how much processed foods gum up your bodily machinery.
Try to avoid excessive supplementation. The only supplements you really need IMO are fish oil, a multivit and MAYBE protein powder if you don't eat that much meat.
Congratulations on the little one and good luck on your journey!