My water broke and I was in full labor 1 day shy of 36 weeks. Twins were born via "urgent" (not scheduled, not emergency) c-section, because one had flipped back to breech (confirmed by ultrasound in the L&D room).
They were 6lbs and 6lbs1oz. The slightly bigger one went to the NICU for suspected fluid in his lungs, was released after about 7 days (totally cleared at that point -- we haven't even been back for a followup). The slightly smaller wasn't even evaluated for a NICU stay -- he was fine and stayed with me.
Wouldn't recommend that route (one NICU, one not) to anyone with twins, but I don't think anyone opts into that situation.
mommy to three boys: A, 3/04
and identical twins B and D, arrived 9/08