Overview

A molar pregnancy — also known as hydatidiform mole — is a rare complication of pregnancy characterized by the abnormal growth of trophoblasts, the cells that normally develop into the placenta.

There are two types of molar pregnancy, complete molar pregnancy and partial molar pregnancy. In a complete molar pregnancy, the placental tissue is abnormal and swollen and appears to form fluid-filled cysts. There's also no formation of fetal tissue. In a partial molar pregnancy, there may be normal placental tissue along with abnormally forming placental tissue. There may also be formation of a fetus, but the fetus is not able to survive, and is usually miscarried early in the pregnancy.

A molar pregnancy can have serious complications — including a rare form of cancer — and requires early treatment.