How can a ovarian cyst affect getting pregnant?

Depends on the size: A small to moderate ovarian cyst should not appreciably affect the chances of getting pregnant. Cysts 3 cm or smaller are considered normal by some doctors. However, a larger cyst (perhaps larger than 5-6 cm) could cause problems with the egg making it into the fallopian tube, and increases the chances of ovarian torsion, which could affect ovary blood supply.

Depends: Usually, it doesn't. Multiple ovarian cysts known as polycystic ovarian syndrome cause woman not to ovulate and therefore not to be able to get pregnant. Many pregnant women are found to have incidental ovarian cysts on ultrasounds done for other reasons and are able to carry pregnancies without complications.