When I was in the third trimester of pregnancy last spring, I began asking about breastfeeding and my various medications. Thyroid was a no brainer, since it's just replacing what my body doesn't make itself. If I had needed insulin after delivery, that was no problem for the same reason. The big issue was taking metformin.

My Ob/Gyn said "Ask your Endocrinologist." My pharmacist said "OH NO, NOT metformin!" My endo said "No, you can't take metformin while breastfeeding." His Physician's Assistant later said "Sure, you can take metformin and nurse, but Dr. Endo isn't comfortable with our office telling you that officially; so do your own research and make up your own mind."

I turned to the internet and as is often the case, my head swam with all the opinions and articles. I learned that there are many studies that "seem to indicate" that breastfeeding may lower your child's risk of contracting Type 1 Diabetes, may lower your child's chance of contracting Type 2 later in life and also may lower the mother's chance of contracting Type 2 later in life. It didn't eliminate my chance - I had gestational diabetes with my son, nursed for 6 months and 18 months after he was born, I was diagnosed with Type 2.

I also saw estimates of how many calories breastfeeding burns from 200 to 1,000 - a HUGE range. I can guarantee you in my case it's not even close to 1,000, though that would be nice.

Finally I found Dr. Thomas W. Hale's book, "Medications and Mothers' Milk" and found that he is considered an expert and his book the "bible" of medicines used during lactation. His website is here. In the end, studies started coming out in 2002 that seem to indicate metformin is ok for lactating women. Then I found out that my pediatrician's office has a lactation consultant on staff with access to Dr. Hale's book and she could have saved me a lot of legwork.

The moral of my story is once again, you have to be prepared to advocate for yourself and do some research. This isn't to say you should flout your doctor's advice. If you are often at odds with your doctor, you need to find a new one or try to resolve your differences. The other message is that in matters of breastfeeding, go to a lactation consultant!