(Image Credit: Joel Ryan/Invision for Parkwood Entertainment/AP Photo)

Beyonce is "feeling much better," a day after a doctor ordered her to postpone her show Tuesday night in Antwerp, Belgium.

The singer posted on her website a handwritten apology to fans for having to cancel the concert. "I've never postponed a show in my life. It was very hard for me. I promise I will make it up very soon. I'm sorry if I disappointed you. Thank you for your concern. I'm feeling much better now and I'm ready to give you a great show."

The "Single Ladies" singer had two shows in Antwerp scheduled for The Mrs. Carter Show world tour. Though it appears the show will go on tonight, there is no word on when the first show will be rescheduled.

(Image Credit: iam.beyonce.com)

Beyonce released a statement Tuesday morning saying she had been "advised by her doctors to rest as a result of dehydration and exhaustion" and that "ticket holders should keep their tickets to be used with the re-scheduled date."

Tuesday's cancellation quickly fueled rumors that the 31-year-old singer is pregnant with her second child. Sources close to the singer have been quick to quash the reports.

"Beyoncé and Jay are planning for another baby after her tour is over and things calm down just a bit," one source told People Monday, referring to the singer and husband Jay-Z.

READ MORE: Beyonce Talks Career, Family and New Movie

In a recent interview with " Good Morning America" in London, the mother of Blue Ivy, who's nearly 18 months old, said she's definitely open to more children.

"I think my daughter needs some company," she said. "I definitely love being big sister."