Pregnancy
Pregnant women in the 3rd trimester may experience sciatica because the enlarged uterus compresses the sciatic nerve when it emerges from the vertebrae to enter the pelvis. Sciatica in pregnant women happens more frequently on the right side.
Ectopic endometriosis
It is a condition characterized by growing of uterus lining outside of the uterus. Endometriosis may grow in the pelvis, causing severe inflammation and sciatic nerve compression inside the pelvis, leading to sciatica.