"Oh my God, I could lose the baby!"

Rihanna has told pals that horrifying thought raced through her mind as her boyfriend Chris Brown brutally beat her - because she thinks she is pregnant, The ENQUIRER has learned.

The talented pop beauty had already told Brown that she might be expecting his baby, and friends fear that may be what triggered his violent rage.

Brown, 19, now faces assault charges for the Feb. 8 attack, but prosecutors are considering adding felony domestic abuse counts and even an attempted murder charge, which could put the R&B singer behind bars for years.

"If Rihanna is pregnant, Chris could have killed the baby," claimed a distressed insider.

Recalling her terror when Brown started pummeling her, Rihanna told friends: "All I could think was, 'Oh, my God, I could lose the baby!'"

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