Pregnancy Risk on Birth Control: Intercourse Near Period & Placebo Pills

Question
My girlfriend and I were having intercourse on the night before
her menstrual cycle begins (oct 2). She had not begun bleeding
yet, but said that she had some light spotting etc that evening
and felt like it would occur as usual the following day. She is on
birth control pills, has been for a few years, and tonight was the
first night to take the placebo pill. We haven't had intercourse in
over a month, and she had her period as usual last month. I was
not using a condom, and had pulled out before ejaculating. I am
worried if maybe some pre-ejaculate fluid had leaked out while i
was still in her. I had urinated prior to having intercourse, does
that kill off any sperm that may still be in the pre-ejaculate
fluid? I am worried that she may become pregnant since she has
started the placebo pill and had not begun actual menstruation
yet. can she still become pregnant and be on her period?

Answer
As long as your girlfriend had taken all of the active pills and had not missed any pills when you had sex, there is no way she could have become pregnnat. If she were not taking the pills, she would ovulate around cycle day #14 and could only become pregnant if she had sex on cycle day #13, 14, 15, or 16  each month. However, since she is on the pill, she does not ovulate and it does not matter if you had unprotected sex on the day before she expected her period (cycle day #22). There are around 300,000 sperm at the tip of the penis prior to ejaculation. Urinating will not get rid of these sperm. However, as long as she was taking the pills (at any time during her cycle) she cannot become pregnant. Don't worry.