Question: When you have sexual intercourse, what is the chance out of ten you will become pregnant if all factors of pregnancy and reproduction organs are normal?

Ed Morrison answered on 20 Jun 2011:

It depends on a lot of factors, but one of the most important is which day of the menstrual cycle sex takes place. Women are in the most fertile period, in other words most likely to become pregnant after sex, for the six days leading up to ovulation. On average, of their most fertile day, women have a probability of 9-13% of becoming pregnant after a single act of unprotected sex. If you have sex more than once, this number will increase.

But remember this is only an average. Any individual couple might have a much higher chance of falling pregnant. So always use contraception if you want to avoid pregnancy.