Milo Ventimilgia and Hayden Panettiere called time on their year-long relationship after a “pregnancy scare,” it's claimed.

The pair – who met on the set of Heroes –  reportedly called it a day last week after the age gap (he's 31, she's 18) apparently caught up with them.

A source said, "It was a lifestyle conflict...(She) is young. She likes to go out in the Hollywood scene and that's not his style. (Ventimiglia) has been concentrating on work, on his production company."

But a new report suggests that “a lifestyle conflict” isn't the whole story.

The Chicago Sun Times reports that, “the split between Hayden Panettiere and Milo Ventimiglia was caused by a pregnancy scare. The test proved negative but apparently caused friction that sparked the breakup.”

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