When you are trying to have a baby does it lessen your chances if you go to the bathroom or wipe your vagina after having sex?

No. Semen travels at the speed of light! == Not to say that you won't get pregnant if you go to the toilet or wipe after sex but it can lessen your chances of getting pregnant. If you're actively trying to get pregnant you might do well to elevate your backside and avoid going to the toilet for around 20/30 mins.