Missing Heartbeat in Early Pregnancy: What to Do?

Question
My mom is pregnant . Her last period was november29 . She has four kids and 6 months ago had a miscarriage . Her first two visits went ok , but her "8" week visit did not go as planned . The doctor said her sack has grown  and it looks normal , but their was no heartbeat . He said the day of conception could vary from what she thought it was and she could only be about 7 to 7 and a half weeks pregnant . her levels were through the roof .She is thirty six   .
please help me in this question , I do not want her to have another miscarriage . Her next appointment is tomorrow .

Answer
If your mom's last period started on November 29, she should now be exactly 6 weeks pregnant (from the first day of her last period). A sonogram at 5-6 weeks usually only shows an empty gestational sac but no fetus and no fetal heartbeat. However, after 6-7 weeks gestational age, we usually see a fetal pole, a gestational sac, and a fetal heartbeat. If whe has not had any bleeding and there is good increase in HCG, you need not worry.  She is only 6 weeks from the first day of her last period. Count it yourself. She cannot be 8 weeks or even 7 weeks pregnant yet. We count a pregnancy from the first day of the last period.