An ectopic pregnancy is often caused by damage to the fallopian tubes. A fertilized egg may have trouble passing through a damaged tube, causing the egg to implant and grow in the tube. Things that make you more likely to have fallopian tube damage and an ectopic pregnancy include: Smoking.

Why do ectopic pregnancies happen?

A tubal pregnancy — the most common type of ectopic pregnancy — happens when a fertilized egg gets stuck on its way to the uterus, often because the fallopian tube is damaged by inflammation or is misshapen. Hormonal imbalances or abnormal development of the fertilized egg also might play a role.

What increases risk of ectopic pregnancy?

Various risk factors for ectopic pregnancy have been identified (2-5) including previous ectopic pregnancy, previous pelvic surgery, induction of ovulation, intrauterine device usage, history of pelvic inflammatory disease (PID), and smoking at the time of conception (2, 6-9).