How can I prevent blood clots during my period? Is this normal?

Yes it is very normal, my sisiter has the same problem, her clots are sometimes the size of golfballs, she got sterilized and the doctor tells her its normal, he even suggested that she go on the contraceptive pill to help reduce the clotting. Hope this is of some help to you but you can be assured that it is perfectly normal.

It is normal to have clots. I'm on blood thinners and I still get blood clots from my period. Birth control didn't help me with the problem... only gave me blood clots... in my lungs.

Many women have clots in their menstrual blood from time to time. The clots may be bright red or dark. Often, these clots are shed on the heaviest days of bleeding. The presence of multiple clots in your flow may make your menstrual blood seem thick or denser than usual.

Your body typically releases anticoagulants to keep menstrual blood from clotting as it's being released. But when your period is heavy and blood is being rapidly expelled, there's not enough time for anticoagulants to work. That enables clots to form.

If you have excessive clotting or clots larger than a quarter, you should see a health care professional to rule out any conditions that might be causing an abnormal period.

Menstrual Blood Problems: Clots, Color, and Thickness (http://women.webmd.com/menstrual-blood-problems-clots-color-and-thickness)