Fetal Heart Rate & Yolk Sac: What to Expect During Pregnancy

Question
Hello,
Is it normal for the heart rate of a 10 week fetus to be 134 during an ultrasound, does this seem too low?? And also,when does the yolk sac disappear, should the yolk sac still be present and will I see the yolk sac at my 20 week scan??

Answer
Dear Daniella,
I'm sorry it took so long to get back to you. I wanted to make sure I had all the correct information for you, and I was busy at births this week, so it was a bit hectic.
Normal heart rate for a fetus is anywhere between 120 and 160, so your baby fits right in. Under 120 would be a cause for concern, but 134 is perfectly normal.
The yolk sac is usually functional until about 10 weeks, and disappears sometime after that when the placenta is fully formed.
The purpose of the yolk sac is not fully understood yet (understandably) because of the controversy surrounding embryonic experimentation.
Best of luck,
Sheva