By Getting Both The Mother & The Father To Sign Very Strict NDA's.

https://www.foxnews.com/entertainment/paris-hilton-kept-new-baby-secret-from-family

And would you look at that.

https://www.dailymail.co.uk/tvshowbiz/article-11660531/Chrissy-Teigen-wears-belly-binder-one-week-giving-birth-John-Legends-baby-girl.html

Some of us seem to be fast running through our second pint.