It seems 'So Yesterday' that mom-to-be Hilary Duff once had a career as a singer -- but she reminded us today over Twitter.

The author, actress, designer and singer wrote, "Very excited to tell u guys I have started my vocal classes again to get in shape!4 the next few months its just for entertainment: ) But yay!"

This could be a rather clever career move, as Duff was recently canned from a 'Bonnie and Clyde' remake. A music career would likely be much more accommodating to Duff's schedule, as she has a baby boy on the way -- she doesn't have to worry about a cast and crew meeting deadlines and can work at her own pace.

Duff's singing career may be more successful than her films anyway. While many of her movies were critically panned or box office duds, her sold out tours proved her clout. In addition, her 2003 album 'Metamorphosis' sold over 3.9 million copies in the U.S. by January 2007, propelled by hit single 'So Yesterday.' Duff also spawned theme songs for two MTV shows: her single 'Come Clean' became the theme song for 'Laguna Beach,' and 'Sweet Sixteen' was the opening music to 'My Super Sweet 16.' She even had enough success to spawn a compilation album, 'Most Wanted,' that debuted at No. 1 on the Billboard 200.

While we'll have to wait to hear Duff's new songs, one person will reap the benefits soon enough. Her future baby boy is sure to love his lullabies!