IUI and swimming

I am starting IUI soon, but I teach swim lessons during the summer. Some places suggest no swimming for 24-48 hours after IUI. Any idea why? Is this for potentail infection reasons? I mean, the sperm is not gonna fall out of your uterus, and when I swim it is not like I am squirting water up my vag. A little water maybe sometimes gets near the entrance, but that is it. What if you used a menstrual cup to cover your cervix so that any water with ninja vag maneuvering skills cannot reach the cervix? I would hate to have to cancel lesson days with little notice, since I never know when IUI will be exactly. What do you guys think?