Sean Preston peers from Britney's hospital window

LOS ANGELES (Reuters) - Pop star Britney Spears has given birth to her second baby in 12 months, according to celebrity magazines, but the middle-of-the-night arrival may not have gone as planned.

Publicists for Spears declined to confirm or deny on Wednesday widespread reports the former teen idol gave birth at 2 a.m. on Tuesday to a 6 pound 11 ounce son at a Los Angeles hospital.

Lifeandstylemag.com quoted Spears husband Kevin Federline on its Web site on Wednesday as confirming the birth, saying "Mom and baby are doing well, thanks, but we're all really tired."

Spears, 24, joyfully announced the arrival of her first child, Sean Preston, on her Web site the day after he was born on September 14 2005. There was no such announcement early on Wednesday.

Lifeandstylemag.com and the National Enquirer said Spear's second baby arrived in a planned Caesarean section, like her first. But In Touch Weekly said Federline rushed Spears to a hospital ahead of time because she was suffering from pre-eclampsia -- a pregnancy-related condition marked by high-blood pressure -- that turned acute.

"The delivery was not planned. It became urgent. Britney and Kevin did not want to take any chances," In Touch quoted an unnamed family insider as saying.

In another twist to the obsessive tabloid media coverage of Spears and her private life, the new baby was not the girl that Britney had led the media to believe she was expecting.

Celebrity magazines had Spears shopping for pink baby clothes and accessories in recent weeks and claimed she planned to name the child Jamilyn after her younger sister Jamie and her mother Lynne.

Spears put her phenomenal recording career on hold after she married Federline in September 2004 but has continued to make headlines.

Child welfare authorities visited her twice last spring after she was photographed driving a car with her infant son on her lap, and after Sean Preston fell from a high chair and hit his head. No charges were brought.

She announced her pregnancy on a late night TV chat show and posed nude for Harper's Bazaar magazine when she was six months pregnant. Shortly afterward she complained she was being hounded by paparazzi and appealed to them to leave her alone.