Britney Spears' 16-year-old sister engaged

Actress Jamie-Lynn Spears arrives at the Us Weekly Hot Hollywood Party at Opera in 2007 in Los Angeles, California. [Agencies]

The pregnant 16-year-old sister of troubled pop star Britney Spears is engaged, it was reported Tuesday.

People magazine reported that Jamie Lynn Spears -- the star of the US television show "Zoey 101" whose pregnancy last year sparked a nationwide debate -- has been showing off an engagement ring to friends.

Her fiance is the father of her baby, boyfriend, Casey Aldridge, People said. "She's got an engagement ring," a source close to Spears told People. "She's been showing it off, talking about it."

News of Jamie Lynn Spears' pregnancy last year came as her more famous elder sister battled for custody of her own two children with ex-husband Kevin Federline amid allegations of being an unfit mother.

Soon after confirmation of the pregnancy, Spears' mother Lynne shelved plans for a a book on parenting.

Lynne Spears had been due to release "Pop Culture Mom: A Real Story of Fame and Family in a Tabloid World" via publisher Thomas Nelson next month.