Hiya, in my honest oppinion LC should not be undertaken by pregnant women or those who are breast feeding. It does state that in the Atkins book. I would strongly suggest that you eat healthily until you have stopped breast feeding - your baby needs all of the nutrients and vitamines in your breast milk to grow and develope, include lots of freash vegies and just be careful about the sugary and starchy things. I would say that you can drop some carbs out of your diet whilst breast feeding, but not to a level where you are following a LC diet.
Good luck and I hope that you get some more responses!