I just had my 8 week ultrasound and both babies are doing great! Both measuring where they should and heart beats are strong, baby A 161 baby B 177.  The only difference between baby A and baby B was the gestational sac size.  Baby A's sac was double the size of baby B's, baby B looked squished in its sac, where as baby A had plenty of room! The dr did not say anything about the size difference and I forgot to ask.  Should I be concerned or could it just have been angel of vaginal us probe?!? I'm trying to stay off google so thought I would ask here, and see if any you ladies had any experience with gestational sac size?!?