Growth Discordance in Fraternal Twins

I am 22 weeks along with fraternal boy/girl twins and the boy (baby A) was measuring in the 90th percentile at 1 lb 7 oz, and the girl was measuring at 1 lb around the 35th percentile.  However, they both looked fine otherwise.  All of their organs looked fine and their fluids were both fine too.  They both seem to be steadily growing.  

Is the discordance something to be concerned about?  I want to realistically know what to expect but I have to wait another 4 weeks for another ultrasound.  Do they have a poor chance of survival just because of this? Thanks.

[AnnieBrooke]

There is a discussion of this topic on another forum, I'll include the link.  It sounds in general as though fraternals develop as though they are singletons, and some babies are smaller than others, so this is of less concern than if they were identicals.

twin stuff . com / forum / index . php ? show topic = 57011  
(Delete all spaces between all words, punctuation and letters.)

[tam2girls]

My boy/girl twins were always different sizes. Sometimes they measured the same and the 2 weeks later he would measure a weeks gestation bigger. She always caught up and even now he has his growth spurts before her and she always catches up. I was told 3 days before they were born that he was 5lbs and she was only 4lbs and that I had best go to a different hospital to deliver them. Well guess what they were delivered at 36 weeks and he was 6lbs and 1/2 ounce and she was 5lbs 13 so the scan was way off. So as long as they are both growing well then I would try not to worry. Good luck

[mysty2001]

my doc says ant discordance over 20 percent is serious
Mine were discordant for a few months and I was heavilt monitored
At one point (over 20 percent) they decided to hospitalize me for bedrest due to discordance - my doc explained that bed rest would allow more oxygen to get to the second placenta

when they were born his head measured a 43 week baby head - but her weight had caught up

best of luck - be sure to ask for the percent discordance (because it is a combo of weights and measures not just the weights)