In this photo released by CBS, pop singer Britney Spears shares a laugh with host David Letterman on the set of The Late Show with David Letterman, Tuesday, May 9, 2006 in New York. Spears announced on the show that she and husband Kevin Federline are expecting their second child. (AP Photo/CBS, Jeffrey Neira)

LOS ANGELES - The baby bump is for real. Britney Spears told David Letterman Tuesday that she is pregnant with baby No. 2. "Don't worry Dave, it's not yours," the pop princess quipped.

The revelation ended weeks of speculation in entertainment magazines, which have been regularly publishing pictures of Spears' apparently expanding waistline.

Spears, 24, and her husband, backup dancer-turned-rapper Kevin Federline, 28, were married in 2004 and have an 8-month-old son, Sean Preston.

Federline also has two children, Kori and Kaleb, with his former girlfriend, Shar Jackson.

Spears rose to fame at 16 with a naughty schoolgirl image and the multiplatinum album "... Baby One More Time."

Britney is still in NYC and today (April 9) she took cute little Sean Preston out for some shopping.Britney Spears and husband Kevin Federline are expecting their second child together, Spears told David Letterman during a surprise visit to his show on Tuesday.