After weeks of speculation by magazines like Us Weekly and Star, Britney Spears officially announced last week that she is pregnant.

Although this may be great news for Britney personally, it certainly isn’t the best news for her career.

The forthcoming bundle of joy is the latest in a long line of moves alienating her young fans. This began years ago, when she admitted to having premarital sex with Justin Timberlake, despite her longtime insistence that she would wait until marriage, Britney lost more young followers in early 2004 after her 55-hour wedding to childhood friend Jason Alexander (not the guy from “Seinfeld”).

Now, after getting pregnant with her second husband, failed backup dancer Kevin Federline (who already has two children from a previous relationship), Britney is sure to lose many of her remaining fans.

The problem is that she no longer has an age-appropriate fan base. The 12-year-olds are too young for the twice-married mom-to-be, and the teenage boys are no longer interested. Unless she decides to change her genre of music — the bubblegum pop style just won’t work for the older crowd — she’s pretty much lost anyone who was ever interested in her.

Britney has said in the past that she wants to be one of the those artists — like Madonna, to whom she usually tries to compare herself — who continues to reinvent themselves throughout their career. Unfortunately for Britney, being a wife and mom at the age of 23 is going to make that pretty hard. How will she ever reinvent herself if no one is listening?

Maybe Britney and Kevin’s upcoming reality TV show, chronicling their engagement and wedding, will draw in an older, more mature fan base who will support Britney and her career through the years.

We’re doubtful.