Forty percent of women with untreated chlamydia will develop pelvic inflammatory disease (PID), a serious disease that is one of the most common causes of infertility.
Chlamydia itself can also cause serious complications with pregnancy. The infection can cause the amniotic sac surrounding the fetus to break. Ectopic pregnancy (pregnancy outside the uterus) is another possible complication. Chlamydia can also transmit to the fetus during labor and cause eye infections or pheumonia.