Are there any herbs that cause a miscarriage?

I am 35 years old and have 3 girls ages 15-1. I have recently gone through alot of medical problems and heartache in my life and I am not ready for another child and my husband is not either. My life was starting to turn around and now this. I have thought about adoption but I would never be able to give a child away after carrying for 9 months. I need help with this if anyone can help let me know!