I have lost 20lbs since I have been pregnant. I'm 12weeks. But my doctor isnt concerned. Is it ok for the baby?

Yes, depends. If your bmi--an index of your overwt or obesity is very high, then gaining wt during preg is dangerous. Let me give you an example. My receptionist was pregnant when very obese. I told her, julie, you cannot gain weight and should in fact loose it. But not unhealthfully. I put her on a strict high nutrition diet. She lost five pounds and her son is 22 yrs old today, in college & doing great!