Understanding Fetal Sac Size and Crown-Rump Length in Early Pregnancy

Question
Hello.  I am about seven weeks 2 days pregnant and my question is regarding small sac vs. crown/rump length of the fetus.  I had a sonogram on Dec. 13 and there was a fetal pole and heart beat.  The sonogram tech said the sac was a little small.  At that time she said I was 6 weeks and 4 days.  I went back exactly a week later and the fetus grew and had a strong heart beat (133) ... It all looked OK except the sac only grew a little bit.  I am going crazy wondering and waiting and wanted to know if there's any hope the sac will catch up and if there's a chance all will be OK?  Is it just too early to tell anything?  My next sonogram isn't until Jan. 17th (I should be about 10 weeks by then).  I am so worried and stressed waiting and wondering.  Trying to stay optimistic.
If you have any information on this, I would appreciate it.  Thank you!  

Answer
Dear Amy,

It is early to be overly concerned about this. In the research that I have found, a small gestational sac early in pregnancy actually occurs more often in normal fetuses than abnormal ones. In the study I found, it occurred in 1.9% of pregnancies scanned with vaginal ultrasound 37-65 days after the first day of the last menstrual period. The success of the pregnancies was most dependent upon how small in comparison to crown-rump measurement the sac was. And the healthy contents of the gestational sac, especially a good, strong heartbeat, are always a positive indication. It is important for you to know that this is not absolutely ominous. Many women do go on to have normal healthy pregnancies when sac size is a bit small in the beginning.

Try not to stress too much over this until you go for your next ultrasound, as stress is not a positive thing for the pregnancy either and there is nothing you yourself can do to change the size of the sac either way. Hopefully, the sac will have grown equally in relation to the baby's growth at that time.

I hope this information has helped you and answered your question. I wish you a blessed and Happy New Year!

Brenda