A molar pregnancy is a pregnancy in which something goes wrong at fertilization, causing the placenta to develop abnormally into a mass of water-filled cysts known as a hydatidiform mole. In a complete molar pregnancy, no embryonic material is present at all, while a partial molar pregnancy may include some embryonic tissue. In the case of a partial molar pregnancy, the embryo is non-viable, and will never develop into a baby.
The cause of molar pregnancies is not really understood. Some researchers suspect that it has to do with ovulation errors, lack of certain nutrients, or random mistakes which happen in fertilization. Around one in 1,000 pregnancies is a molar pregnancy, and most of the time, the pregnancy aborts spontaneously. Women should certainly not feel personally responsible if they experience a molar pregnancy, as there is nothing to be done to prevent such pregnancies.
In the early stages, a molar pregnancy can feel like a normal pregnancy. Hormone levels go up, and swelling of the abdomen may be experienced. However, an ultrasound will reveal that the uterus is filled with a mass of cysts, not a developing embryo. Most doctors recommend terminating a molar pregnancy if it does not spontaneously abort, because it can turn cancerous, threatening future reproductive health as well as the life of the mother. People who have moral qualms about the termination of pregnancy can be assured that a molar pregnancy represents no potential for viable life, and therefore it is not equivalent to a normal pregnancy.
You may also hear molar pregnancy referred to as gestational trophoblastic disease. In very rare cases, a molar pregnancy develops alongside a normal pregnancy. In these instances, a doctor may recommend that the mother carry the regular pregnancy to term, assuming that the mole will resolve itself in the process of gestation or labor and delivery. Routine testing may be required as a follow up after the birth to confirm that the mole has been totally expelled.
While a molar pregnancy isn't a “real” pregnancy, it is still a pregnancy loss, and it is appropriate to grieve after a molar pregnancy. Women with such pregnancies feel like they are pregnant, complete with physical and hormonal changes, and it can be jarring to learn that the pregnancy was false. Most doctors recommend taking a break from trying to conceive after a molar pregnancy, to ensure that the mole is entirely gone and to give the body a rest.