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I'm having trouble understanding what my girlfriend is explaining to me. Today (3/21) she found out from her doctor that she is 9 weeks pregnant (which dates back to 2/17), but that the date of conception was 7 weeks ago (which dates 3/3). The reason I am asking for a clarification, is that I was away during the 2/17 time frame, but I was around during the 3/3 time frame. She tells me that the week number is done kind of weird. So what is the case?                                                                              Thanks, Angelo