Beyond the on-air battle for ratings, wardrobe spies say female staff at the network's Willoughby bunker have been warned against wearing this season's flouncy-shaped frocks to work.

The reason is so their bosses don't mistake them for being pregnant.

Channel 9 female staff such as Lara Bingle have been warned against wearing founcy -shaped frocks so their bosses don't mistake them for being pregnant.

The summer-style dress, which billows out from under a woman's bustline, is a hot look in stores right now and is popular for the comfort factor and its easy chic.

But the frock's loose-fitting style can pose a problem for those tricked into thinking: "Is she or isn't she (pregnant)?"

It has obviously proved a challenge for the PC-paranoid executives at Channel 9, who have been trying to kick their apparent foot-in-mouth habit with female employees.

This latest fashion measure follows the infamous "boning" drama which implicated Nine CEO Eddie McGuire with plans to sack Today co-host Jessica Rowe.

Ironically, Rowe has made the empire-line frock a staple in her maternity wear wardrobe since announcing her pregnancy in July.

But other network talent, including Lara Bingle, Sami Lukis and Toni Pearen have all worn the empire style on air - in Bingle's case while skating on thin ice.

A Channel 9 spokesman last night denied the style advisory, adding "most people here wouldn't know what an empire line dress is, let alone asking them not to wear one".

However, wardrobe edicts are nothing new - but always controversial - in the serious race for ratings, as all the networks groom their stars for success.

Former Nine boss, now Channel 7 CEO David Leckie apparently issued his "jugs under the chin" directive to female TV presenters as a priority when he joined the station in 2003.

At Channel 10, Sandra Sully's skirt lengths made headline news last year after her bosses redesigned the studio set to reveal too much of her legs for a few viewers liking.