"We are happy... Very happy about it (Saif and Kareena's baby). We are very excited," Soha told reporters here at an event.
Saif had last month confirmed that the couple was expecting their first child in December.
The actor, who was earlier married to actress Amrita Singh, has two children with her - daughter Sara and son Ibrahim.
Following a five-year courtship, Saif, son of Tiger Pataudi and actress Sharmila Tagore, tied the knot with Kareena, daughter of actors Randhir Kapoor and Babita, in October 2012.