Rachel Bilson's rep has brushed off rumours the actress is expecting her first child with fiance Hayden Christensen, insisting there is "absolutely no truth" to the speculation.

The former The O.C. star sparked speculation she was hiding a baby bump after she was photographed heading into a doctor's office at the weekend (06-07Feb10) wearing an oversized rain jacket.

Rachel Bilson and Hayden Christensen, both 28, announced their engagement in February 2009, but her spokesperson insists the couple is not starting a family just yet.

Her rep tells UsMagazine.com there is "absolutely no truth to (the rumour about) Rachel being pregnant".