The pregnancy rumours were sparked by Star magazine, which claimed that the actress was sporting a baby bump at a recent Hollywood event and also backed out of promoting her film Lay The Favourite at the Sundance Film Festival.
A spokesperson for Zeta-Jones told Gossip Cop that the pregnancy report is "not true".
Zeta-Jones's rep added that the actress is not able to attend the Sundance Film Festival because she is currently filming Broken City with Russell Crowe in New Orleans.
She and Douglas are already the parents to 12-year-old son Dylan Michael Douglas and 8-year-old daughter Carys Zeta Douglas.
Zeta-Jones will next co-star with Tom Cruise and Russell Brand in Rock of Ages, opening on June 15 in the US.
> Catherine Zeta-Jones joins Steven Soderbergh's Side Effects
> Rob Brydon: 'I stole Catherine Zeta-Jones's lunch money'
Watch a trailer for Rock of Ages below: