I was in ketosis (not on purpose) during my second pregagncy and she is my healthiest child. I would not try and lose weight just focus on nourshing your baby at a carb level that you feel well at. I felt really good eating lower carband had a very healthy pregnancy (I did not even get a cold). I also ate a lot of greens, homemade bone broths, and chicken liver pate. (Check out www.westonaprice.org)
Many high nutrient density foods are lower carb foods.