The closer you are to ovulation, the bigger the risk/chance of getting pregnant when you have sex.
In the drawing you can see how big the chance is of getting pregnant when you have intercourse once.
When you have sex during your period you have 0,1% chance of getting pregnant. But when you have sex mid-cycle the chance is well over 10%.
Never think you can easily have unprotected sex when the chance of getting pregnant is small. When it comes to the individual thinking in terms of chance doesn’t work. Some take risks all the time without any harm, while others risk something once and are the sucker right away.