Twins and Low Fetal Heartbeat

I had my first ultrasound at 6w3d and found out I am having twins.  One baby had a heartbeat of 100 and the other was 80.  I am very worried about it because my doctor said the baby with the heartbeat of 80 has a 50% chance of survival.  Has anyone had a low heartbeat around 6 weeks?  What happened?

[vsentz]

Sweet heart, i am very sorry about this....(((hugs)))...my US was when i was 6w and my baby's heart rate was 95....he passed away some days later and everything else kept growing...unfortunately we didn't discover it till i was 12 weeks.
There are miracles in this world hon, unfortunately that is a very low hr, I really hope yours turn out to be a miracle and that you are surrounded by a big blessing.
God bless you and your babies!

[MelzieWelzie]

According to this article a normal hb between 6 & 7 wks is 90-110.  
http://www.americanpregnancy.org/pregnancycomplications/earlyfetaldevelopment.htm

Also, a woman who posted here a while back said her fetus had a hb of 75 at 6 weeks and a few weeks later it was at a healthy 143.  The dr. told her that they must have caught the 1st hb close to the time when it had started beating since they tend to start out slow and work they're way up.  Hopefully everything is fine.  I'm sending positive thoughts your way.

[ama67]

I had an u/s at 6 weeks and they saw two sacks one had a 103 hb the other had no heartbeat they didn't see the second heartbeat until 8 weeks then it disappeared again.  My doc. said it is called a vanishing twin and it is more common than realized the only reason why it was detected was that an ultrasound was done so early u/s usually aren't done till later in the preg.  The other baby is fine so we are very blessed.  Best of luck with everything.