Can an cause a baby to become breech?

I know this may sound silly but as a first time mom every and anything worries me. I'm 36 weeks pregnant and the babys head is down in the pelvis where it's supposed to be and I really want the head to stay there. Well I just wanted to know if having an can cause the baby to turn around and become breech? because s cause the uterus and cervix to contract. are s safe right now? how would I know if the baby became breech?