Ovulating by itself doesn't matter, but if you are TTC, then you are most likely having sex around this time. The semen / fluid could interfere. They say you shouldn't have sex the night before or the day of a pap - it could make the test come back abnormal. It doesn't always, but it could.
there was a discussion about this a while back. some people's doctors advised against it and some didn't say anything. I probably wouldn't have sex the day before/day of the exam because I wouldn't want to skew the results in any way