At 7weeks pregnant my baby's growth was excellent as was the heartbeat but I had a yolk sac measuring 7mm the following week, growth and hearbeat right on but yolk sac 9.2mm. I am now just over 11 weeks and measuring exactly what I should, heartbeat 163 (the yolk sac is going down). I worry about the yolk sac indicating chromosonal abnormalities. What are the chances of me having a healthy "normal" baby?