at your son hiding meow! DS saw a birthing scene on tv (you know the typical scream then out pops baby), so he has an idea of what happens. "mummy noisy. baby come out of mum's bum"
Great news that you Aunt will be there for your DS.

Awwww at those girls Cassius. how cute! sounds like your friend is a very handy one to have - midwife and calmbirth instructor!