Ahh I seeee, that makes sense then I didn't know if it was just pot lucky who got to be which number. So can they tell if they have swapped sides etc which baby is which? Sorry for all the questions! xxxx
None of our twins on here would swap sides completely because we all have the kind that are in separate sacs so they roughly stay to their own sides, although the membrane isn't rigid so they can go transverse and kick each other through the membrane and stuff!
If you're interested (probably boring but I've learnt a lot about twins this year)!.. there are four kinds of twin, mine are MCDA and I think the other twins on here are all DCDA.
DCDA:
Dichorionic
diamniotic (2 placenta, 2 sacs) - account for about two-thirds of twins and roughly 3 in 100 births, usually means twos eggs were fertilised but actually can be identical still as sometimes the one egg just split really early and formed two placentas AND two sacs, least high risk out of all twin types.
MCDA:
Monochorionic
diamniotic (1 placenta, 2 sacs) - account for about 3 in 1000 births, one egg split and babies share a placenta but are in separate sacs, fairly high risk due to possibility of twin-to-twin transfusion syndrome (occurs in 20%) and growth issues from sharing placenta.
MCMA:
Monochorionic
monoamniotic (1 placenta, 1 sac) - very rare account for just 1% of identical twins, one egg split into two but it split a little later so twins share both a sac and a placenta, risk of cord entanglement to babies as well as same risks as MCDA twins, very high risk.
Conjoined:
Monochorionic
monoamniotic (1 placenta, 1 sac) and attached - v. rare approx. 1 in 200,000 live births, one egg split but very late and so babies share placenta and sac AND they are fused together, very very high risk as only about 5-20% survive
if they even make it to birth.