Question for you, although I really should know this. Do identical twins share the same amniotic sac?
Good question. Yes, identical twin almost always share one sack...but if the split of the fertilized ovum occurs early (very early) each half can develop their own placenta. This is rare. Most ovum split later and share one placenta. One placenta (post delivery) equals identical twins; two placentas equals fraternal (a quick way to tell if boy/boy twins or girl/girl twins are not identical, of course blood work confirms this). I always smile when boy/girl twins are questioned as 'identical'.