As trillian has said its great for clearing out the passages(all of them ) but also the release of hormones are so benificial for mum and her feelings(baby blues) the natural hormone oxytocin is the love hormone that makes us feel all gushy and also the adrenalin keeps us awake for those first few hours until bubs goes to sleep.
and in the long term for your baby it means that those hormones were recieved and will do what they need to in babies body