My 24 years old sister is now 9 weeks pregnant (14th July 2008) and she doesn't know who is the father either my boyfriend, Ricky or her currently boyfriend, Michael. Break my heart that my boyfriend possible is the father but I need to know who is really the father. I don't know much about pregnant, don't know who it's work so, here's the timeframe.....on march 24th, my sister had sex with Michael. On April 4th, she had sex with Ricky behind my back. 2 weeks later, she had sex with Michael so who would be the father. My sis told me that when she came home from Ricky after having sex, she happened to have her period. Would it prove that Ricky won't be the father??

Please help, am very confusing. I don't want to lose my boyfriend but it's a mess, I will have to.