Should I or not?
Your period doesn’t slow down or stop in water — it just may not flow outside the vagina because of the counter pressure of the water.
It’s natural that your daughter might be anxious about taking part in PE or swimming lessons when she has her period, especially as young girls who have only recently started menstruating are less likely to be using tampons or menstrual cup. A tampon will absorb water from the pool even when it’s inside your body. As long as you spend a relatively short time in the water (an hour or less), and change your tampon right away, wearing a tampon while swimming is still pretty safe. Swimming is not feasible while wearing sanitary pads as the pad would soak water and leak blood. Not nice for others swimming!
If this is the case, speak to your child’s teacher about how the situation can be handled. She’s likely to be encouraged to take part in as much of the lesson as she can, but some allowances might be made – for example, she might be given permission to watch swimming from the spectator seats, or hand out and collect sports equipment instead of taking part in the game herself.