Pregnancy viability

Patient: I am wondering if it is at all possible for a baby to survive if it does not grow for three weeks. My baby measured 6 weeks between weeks 6 thru 9. The heart rate was only 60 at my last ultrasound. I should be 11 weeks today and I’m not having any problems. We postponed any more ultrasound until after 12 weeks. I did have a miscarriage around 10 weeks in September and my thyroid tested on the high end of normal which led them to prescribe me 50 mcg of Levothyroxin.