Well, on a long term basis, steroids should not affect your ability to get pregnant. However, while being on cycle it is very hard to predict, because lots of hormonal changes will take place in your stomach.
Therefore, while you are getting prepped for the competition, better use some contraceptives, because you can not predict the pregnancy while being on cycle. Obviously, don't use hormonal contraceptives, as they may not work as well while using oral steroids.
You can also consider using SARMS, as they are very effective as well, but there will be absolutely no problems at all in the future because they are non-hormonal, and there will be no side effects.