According to reports, Richie and boyfriend Joel Madden discovered that they were expecting when the Simple Life star took a home pregnancy test in early May.
The couple have not confirmed or denied the reports since then, but sources say that Richie is nearly four months pregnant.
"They both wanted kids and decided this was a good time," Us Magazine.com quoted a friend, as saying.
Meanwhile Richie has been sentenced to four days in jail for driving under influence of marijuana and a prescribed painkiller.
Nicole also agreed to serve a three-year probation term and must undergo alcohol education. The socilaite was also fined 2,048 dollars.