Elizabeth Banks and Jennifer Lopez are the only actresses cast as pregnant women who have children in real life; Lopez gave birth to twins, Banks has two sons via a surrogate. Cameron Diaz, Anna Kendrick, and Brooklyn Decker have never had children.
During the ultrasound scene, all of the couples are told the sex of their embryos. However, all of the pictures are side views, which wouldn't show the genitalia.
When Rosie and Marco are in the hospital, Rosie is clearly wearing make-up, despite the fact that she woke up in the middle of the night prior to going to the hospital.
Wendy: I just wanted the glow. The one that they promise you on the cover of those magazines. Well, I'm calling it - pregnancy sucks. Making a human being is really hard. I have no control over my body or my emotions.
Yes, it is inspired by the best-selling book 'What to Expect When You're Expecting' written by Heidi Murkoff and Sharon Mazel. The book itself doesn't have a storyline. It is a pregnancy guide for parents.