The 31-year-old, who is also famous for reality TV show, "The Hills", made an announcement on her personal blog that she and husband Tim Rosenman are expecting a baby.
"When two people love each other so much and the love becomes too great to fit inside both people, it spills over into a THIRD person.
"This is how I am going to explain where babies come from to the little baby that is now growing inside my belly because Timmy and I are PREGNANT!" wrote Whitney.
She also shared several photos of her first maternity photo shoot with Cole Mosberg.