Umm, she had sex with Edward? Wow.. Duh. This is the long story. So, they were on Isle Esme(yes, they own a small island) for their honeymoon, and Edward was reluctant to... you know. Bella said she would stay a human forever if Edward had sex with her, so they did. She was bruised the first night and Edward hated himself for it. He refused to do it again. She wore some fancy "underwear" and seduced him into doing it again, but then she realized that she had missed her period. Then a few weeks later- BAM! She had her baby girl, Renesmee.