Second Embryo Has Weaker Heartbeat

Jane Foley's picture


Dear Ms Ultrasound,
My wife and I just did the 7th week ultrasound. The embryo was at exactly 7 weeks, 0 days which is good. The heart beat seems good as well. The problem is that there is another embryo in the same sack. It's at 6 weeks, 4 days and has a less strong heart beat. Our doctor told us that there were three possibilities listed in terms of probability.

  1. The second embryo will vanish and the first one will continue on
  2. The two will develop two separate amniotic sacks and we will have identical twins
  3. The second embryo will develop within the same sack as the first one and cause problems with the development and in a worst case scenario necessitate an abortion

How concerned should we be?

Thank you,


Dear Doug,
Wow, that is a lot of information from one early ultrasound. Please note that twins never measure exactly the same and their heart rates are always different. This is normal. You are only talking about a 3 day difference between the 2 of them.

I think before you and your wife go into serious worry mode, you should wait and see what the next ultrasound shows. Those early ultrasounds can cause so much anxiety. Many times when a Mom returns for the second ultrasound, and enough time has lapsed for growth (10-14 days) the cause for anxiety is gone.

For now consider one fact: There are two little lives which have been created. Stay positive and nurture them mentally and physically. My belief is that the mental state of mind is so important for good healthy development.If after your next ultrasound you have more questions, please write me and let me know what concerns you may have.

-- Jane, RDMS