The pedantic among you will say this is more of a tip than a secret, I know this because my own nature is causing a civil conflict between the pedants and the mockers living in my brain.
Regardless of the inner turmoil and my fear of promoting miss-categorisation, this tip shall be deemed a secret.
Simply put, don't laugh at her. Ever.
You may well find it amusing that she is sobbing into her pizza over Grey's Anatomy, which incidentally is being shown 5 days a week with back to back episodes. Thank you NET5 for that. Bastards.
But don't laugh.
You may even find it hilarious when the grump with a bump is sitting distraught on the side of the bed in her underwear, having tried on and discarded both her normal clothes which are too small now, and her maternity clothes which are still a bit too big.
You may almost run the car off the motorway from shaking with stifled laughter when she phones you on your way to work in floods of tears because she can't find her shoes.
She knows how to grow new arseholes, so will quite happily tear you a new one.