I'm going to go ahead and give the disclaimer any time that I begin writing about a topic. Please do not take my advice as gold. I am not familiar with you personally, or your pregnancy factors. Your doctor needs to be the one to look into all of that. I think that having a nutrition in place when becoming pregnant though is one of the coolest things that you could do for your baby.
Many times, when girls get pregnant they think "Well I don't need to diet anymore" and just forgo anything to do with nutrition in pregnancy. I think that pregnancy for a lot of women = get out of jail free card = eat all the things. If this gives you peace with food, then by all means I'm a huge fan of your mental state being the first and foremost thing that you take care of. However, there are general guidelines of what you should do, so I wanted to share those with you. As I'm giving this advice though, I always say to keep one thing in mind...listening to your body's signals. You really need no other reason to eat other than-you are hungry. If you are hungry, this is not the time to not eat. You are growing a beautiful miracle inside of you but obviously that baby is going to need nutrition.
When making food choices during pregnancy, this is the one time that I'm actually going to advice for food selection more closely. I always make a big emphasis on just food freedom, and I think that everything should be in balance #duh but how amazing to spend 9 months nourishing your baby to the best of your ability. Pick foods that are colorful and of this earth not all the processed junk. If you just simply eat whole foods, you don't have to worry about all of the things that are restricted in pregnancy. I'm sure you've heard of them but things such as deli meats, cheese, soda, etc. Just stick with plants, and you're golden. I know that's so vague, and who can eat plants all the time Katie? Believe me. I totally understand, so let's move into macros and how that's affected.
Lastly, everyone wants to shout AVOID CAFFEINE like it's the plague in pregnancy. You don't want to end up with a child that's bouncing off the walls, but in reality if you look to the actual literature and studies, there is very little evidence to support that moderate amounts of caffeine are not okay. So, if you like to enjoy a cup of coffee in the morning then by all means, please do not take that out of your day just because you are pregnant. Also, not that soda is good for you, but if you are having one diet soda per day, you are not going to die and your baby is not going to be ADHD because of it. #BALANCEINEVERYTHING
When you first get pregnant, in the first trimester, you literally need no extra. You are not "eating for two". Your baby is the size of your pinky finger. haha! If you are following a macro breakdown, then you would just stay exactly as you are. If you were just starting macros, that's totally cool too. You could just do macros for two weeks, monitor your weight. If you lose weight, then you know that you need to go up on your food because you might be eating too little. I always think that pregnancy is such an awesome time to reverse diet. I am totally making that up with no science to back it but what better timing than to slowly increase food over time. This way, the further you get along in your pregnancy, the more food you are eating. WIN.WIN. That's what I plan on doing. haha!
However, if you are just eating the same and you get to the second trimester, you definitely want to add some food, and the recommendations are 300 calories. That's very arbitrary I'm sure and something that they chose to be studied in clinical trials, but it's a good place to start. One thing of note is that a lot of it should be in protein. Yep. I know. It's not that exciting. If you were to add 300 calories in protein alone though that would be 75g extra of protein so that's a little excessive on top of what you are already doing, so I would say split that up, maybe add 30g protein and then the rest split 50/50 between carb and fat. The reason that you want protein is obviously for the growth and development of the baby.
During the third trimester, the recommendations are 500 calories from your baseline so that is 200 calories above your second trimester. This again, is just an arbitrary number with "mostly protein" so I think that you can use discretion in this, not worry about hitting exact macros, but rather more of a calorie thing and just making sure that you are getting adequate amounts in for the growth and development of the baby.
Your doctor I'm sure will also recommend that you take folic acid and vitamin D for proper development as well.
The recommendations are pretty simple, and easy to follow so nothing too intensive to share, however I also want to go ahead and say again that I'm not an expert on pediatrics and I do NOT replace doctors advice. There are many times that women have situations where they have to avoid certain foods, eat more, eat less, eat less salt, etc so I just want you to make sure that you are taking care of you first, and ALWAYS listen to your hunger signals. They are there for a reason! :)