I'm having twin boys. I'm 30 weeks pregnant and by the time they checked to see if the boys were identical or fraternal it was too late. I was told it's harder to tell the further along you are and they initially checked at my first growth scan at 20 weeks. They don't share a sac. The placentas are either fused together or it's one placenta. At any rate at my 28 week growth scan baby A measured approximately 3.5 lbs and baby B was 2.75 lbs. That's almost a pound difference. My MFM wasn't too concerned at the time but when I saw my OB a week later, he said he wanted to keep an eye on it. Neither one is small for their gestational age, and my GD test is negative (I'm quite thin...with a giant belly), but I'm wondering if there's a cause for concern about the size difference. The aminiotic fluid in both sacs is fine, and is the exact same in both. I have mild polyhydramnios but I have this entire pregnancy and I'm not gaining fluid. It's been the same for weeks. I can feel the feet of baby A, who's head down, and sometimes I can feel the hands of baby B who's breech. But even just looking at my stomach when I sit down I can see that one side is bigger than the other. Since the doctors aren't for sure that they're fraternal I'm wondering if the size difference is significant and if any of you in this community have dealt with the same issue and what the outcome was. I know there can be a significant size difference in boy/girl twins so I'm more interested to know about you all who have had significant size differences when having same sex twins. Thanks.