Eating habits are a very sensitive topic since there are so many food sensitivities and dietary styles. My professional experience and personal experiences have meshed into these viewpoints.
You are eating for the sole purpose of nourishment and you will not feel satisfied if you are eating foods that your body does not want. That is why you can eat a whole pint of ice cream or a whole bag of chips and feel sick but not satisfied. It is important to be aware of how balanced your daily foods are and to know if your body is telling you that you are missing something.
Protecting your Own Health
The woman's body is made to take care of the baby first. So if the mother is not consuming her nutritional needs during pregnancy, the body will take it from other parts of her such as her hair or her teeth. The body will also hold back nourishing the baby in these areas too. Mothers who were undernourished during pregnancy especially the first trimester (or had pregnancies too close together) often experience tooth issues after pregnancy or have children who have tooth decay at a very young age. This is important stuff and just popping your prenatal vitamins does not ensure proper nourishment!
Food cravings are a wonderful clue. Our body often gives us a craving when it is missing a nutrient. The craving usually says "I need something now!" and we often misinterpret that to mean "I really need the jelly donut that I just saw." During a time of craving, it is good to take a step back and deconstruct why you are having it. Are you thirsty? Are your meals and snacks well rounded enough? Are your fruits and vegetables filled with varying colors (especially dark green)? Are you getting enough protein? Are you getting enough whole grains (not from "whole grain flour" but the real whole grains like brown rice, quinoa, millet, etc.)? Are you getting enough healthy fats (raw olive oil, coconut oil, grass fed butter, etc.)?
Deconstructing your craving can be complicated and I suggest that if you are having regular cravings that you write down everything that you eat daily and try to work out a pattern from day to day. Maybe you need to change up your breakfast (add some veggies or protein) or add some sweet vegetables to your lunch (beets and carrots are great with dark greens). When you stop having cravings then you know that your body is in balance.
I have deconstructed many times and now I often crave kale if I am lacking my dark greens. When I accidentally have not had fruit my mind cannot stop thinking about gummy bears (oh how I love you little guys!).
Nutrient Dense Foods
Calories are not just calories when it comes to being pregnant. Your body needs certain nutrients in their most wholesome form so you can absorb them best. This means that it is best to get your serving for fruit from a piece of fruit and not from juice (that lacks active enzymes, fiber, and nutrients). Your body has no need for soda or flavored waters that are filled with chemicals.
Traditionally most cultures had special foods for pregnant women. They were given the liver, the fatty pieces of meat, bone broths and nutrient dense grains such as quinoa. If you follow a traditional diet, you will know that these foods are staples for pregnant women. Dr. Weston A. Price discovered almost a hundred years ago that people who still follow these traditional diets while pregnant and while children are young, have the best health and perfect teeth.
I do believe that some people find their optional health while being vegetarians or vegans and that some people find that their dietary needs change during different stages of their lives. Yes, there are plenty of healthy vegetarians and vegans that have healthy babies but you must be careful to make sure that you are eating enough nutrients. I have also met some vegans who attribute their child's growth delays and teeth decay to their lack of nutrient while pregnant. People of all dietary types can fall into the junk food trap of eating protein bars, processed foods (including processed soy), too few fresh fruits and vegetables, and not enough or the wrong types of fats. Take a step back and look at what you are really eating.
Don't Forget the What to Eat List!
Wow, I could write a book just on prenatal nutrition so I will just stop this post here :)