Britney Spears' birthday is on December 2, but if you're planning to send her a lavish gift, skip it: the singer wants people to give back this year for her special day.

Britney has tweeted a link to a fundraising site for St. Jude Children's Research hospital, which contains a message from her asking her fans to give generously to the charity. "It's that time of year again when we pause to reflect upon what we're thankful for. I'm thankful to have the most amazing fans in the world who have been there for me through everything!" she writes.

Noting that December is very busy for her, what with the release of her new album and the launch of her Vegas show, she adds, "This year, I'm doing something different for my birthday. I'm dedicating it to the kids of St. Jude. Help me out by not buying me a gift this year. Buy them a gift instead -- the gift of another birthday."

Britney goes on to note that since the hospital opened in 1962, St. Jude has helped increase the overall childhood cancer survival rate from 20 percent to 80 percent, and adds that the hospital never charges families for treatment, "because all a family should worry about is helping their child live."  "That's right: the best care in the world, for free, because of people like us. Now that's something worth celebrating. Let's get this party started," she finishes.

In other Britney news, her little sister, Jamie Lynn Spears, has released her first single, "How Could I Want More," to great reviews.  The sweet country song is about a woman in a relationship with a great guy.  The lyrics go, "All he does is love me/ He swears that's what he's here for/So, how could I want more?"  It's available now on iTunes.

"This song means a lot to me... Hope it does to ya'll as well!! Love y'all!!" she tweeted.  Jamie Lynn also makes a guest appearance on big sister Brit's new album Britney Jean.