Twins weight


Just a bit concerned. I had my 37 week ultrasound today, Baby A measured in at 4lbs 15oz and Baby B measured in at 7lbs 4oz.... They have not been able to confirm that the girls are di/di because of the way my placenta/placentas are sitting. My question is, doesn't this seem like a large difference in size? Since 20 weeks they've stayed with in 10oz of each other... Then this jump. I haven't googled cause I'm scared, any mama's have advice here??