Is it possible to get pregnant 3 weeks after the first day of your period? My friend says she doesn't believe in trying on your fertile days, because she was avoiding sex around her fertile days. She got her period at the beginning of one month, finished on the 6th and didn't see her boyfriend till the 20th when she concieved. I didn't think it was possible to get pregnant that late after your period? Unless she had a really long cycle, but I don't think she did. And if she ovulated late on in her cycle, how would the egg have implanted?