Hello, and I hope I can help you today. Any activity you do that does not hurt you physically will not affect your ability to conceive nor will harm you if you are pregnant. So you can ride the roller coaster, run, or do any of the activities you usually do to enjoy life and stay healthy, and it will not harm you or interfere with your fertility. The one thing that you may want to consider is that your uterus needs time to heal from a Cesarean section and it is generally recommended you wait one year to become pregnant again to allow the uterine scar to regain full strength. Women who get pregnant sooner after having a c-section are at increased risk of abnormal attachment of the placenta, and of rupturing their uterus if they go into labor. I am sure after your last delivery you want to try to conceive right away, but the safest thing would be to wait until a full year passed since your c/section. I hope i was able to adequately answer your question today and that this information was helpful to you. Best wishes for your next pregnancy, Dr. Brown