Hi K.,
I became pregnant with this baby when my son was 2 months old. I've never had a problem with milk supply, but when my son was 3 months old, I noticed that I was not producing as much, and my let downs were less frequent. I was like WHAT IS GOING ON? I also stopped losing weight, and I was totally confused!
So I started supplementing with formula here and there, when I thought he needed it. Soon, I started feeling so tired that I could not stay up past 7 in the evening. Pregnancy never crossed my mind, until I started noticing that things seemed especially strong to my nose, and I started feeling sick. I took a test, and lucky me, it was positive! I continued to nurse as long as I could...but soon I realized that I was going to have to eliminate one of the demands on my body, and since I could do nothing about the baby on the inside, I stopped nursing my son. It was an agonizing decision, though, as I had always breastfed my other children to 18 months or so.
My Doc was fine with me continuing to nurse, but she did warn me to continue to take my vitamins, and to baby myself whenever possible. We started giving our son Similac, and he did just fine with it. He is almost 10 months old, and he loves his bottles! As long as you don't have any preterm labor issues, or anything like that, I would imagine that it would be okay for you to continue, but talk to your doctor. Make sure that you let her know how important continuing is to you. Congrats on the new little one! I say if you can keep going, then do it! It is so rewarding.
K.