According to some media reports, the couple visited a doctor in London for a check-up and the sex determination recently.
"The report is completely baseless and the couple strongly denies any such incident. There was no such discussion with any doctor in London and the report is purely a figment of someone's imagination," spokesperson of both the actors said in a statement here.
"Kareena and Saif are both mature adults and are above all this. We would like to request everyone not to unnecessary sensationalise a private issue," the spokesperson added.
Earlier, superstar Shah Rukh Khan had faced similar accusations when his son Abram was born.
Saif has two children -- daughter Sara and son Ibrahim -- from his previous marriage to the actress Amrita Singh.
On work front, Saif will be seen next in Vishal Bharadwaj's "Rangoon" while Kareena will begin work on her next film "Veere Di Wedding" alongside Sonam Kapoor, Swara Bhaskar and Shikha Talsania in August this year.