Pregnant women need additional proteins in pregnancy, mainly in third trimester.
The requirement of protein is about 70-90 g in pregnancy, depending on the weight.
In the first two trimesters, you need protein (grams) =1.2*body weight
In last trimester you need protein (grams) =1.5*body weight
Now I would advise taking most of these proteins via diet. So my first advise would be-
1) visit a nutritionist and get a diet chart made-
However, sometimes it's not possible to eat lean chicken every day or even a boiled egg. And if you are vegetarian, in all possibility your diet will be deficient in proteins, hence you will need supplements.
Coming to protein supplements- there are a variety of supplements in the market, however, not all of them are good for you in the following ways-
A) they may also have vitamins- now you are already getting vitamins through your prenatal vitamin, and this additional vitamin from protein supplement can cause toxicity of some vitamins.
B) whey-based proteins will not be good for women with lactose intolerance as whey is derived from milk.
C) artificial sweeteners/flavouring agents-can be toxic to the fetus
D) the protein powder meant for bodybuilders won't be good for pregnant women as they may contain ingredients/hormones not suited for the fetus
Hence to choose the best protein powder to take the following things into mind-
An ideal protein powder:
1) should have pure protein and minimal additional constituents. As a rule of thumb- if you can't pronounce it, don't eat it!
3) lactose intolerant or dairy sensitive women should go for pure pea protein powder instead of whey protein
Have a healthy baby. Enjoy your pregnancy.