Having sex or having an orgasm can cause the uterus to contract. This most often isn't a reason to worry.

But your healthcare professional might suggest not having sex if:

You have vaginal bleeding.
You leak amniotic fluid.
Your cervix begins to open early, called cervical incompetence.
Your placenta covers your cervical opening partly or all the way, called placenta previa.
You have a history of starting labor early or giving birth early.