Molar Pregnancy

Molar pregnancies occur when there is an abnormality with the placenta at the time of fertilization of the egg. They can be either “complete” or “partial.”

A complete mole occurs when the nucleus of an egg is either lost or inactivated. The sperm then duplicates itself because the egg was lacking genetic information. Usually there is no fetus, no placenta, no fluid, and no amniotic membranes. The uterus is rather filled with the mole that resembles a bunch of grapes. The fluid-filled vesicles grow rapidly, which can make the uterus seem larger than it should be for gestational age. Because there is no placenta to receive the blood, typically you will see bleeding into the uterine cavity or vaginal bleeding.

A partial mole most frequently occurs when two sperm fertilize the same egg. There may be partial placentas, membranes, or even a fetus present in a partial mole. However, there are usually genetic problems with the baby, such as too many chromosomes. Rarely, a partial mole will exist with a twin pregnancy; however, the twin rarely survives.

Symptoms and Diagnosis

Symptoms of a molar pregnancy can include increased nausea and vomiting of pregnancy, beyond normal morning sickness; vaginal bleeding; increased hCG levels; rapidly growing uterus for your pregnancy dates; pregnancy induced hypertension prior to twenty-four weeks; no fetal movement or heart tone detected; and hyperthyroidism. Diagnosis is varied for this type of pregnancy loss. Most of the time a molar pregnancy will end spontaneously.

When the woman passes tissues that appear to be grapelike and shows them to her practitioner then a molar pregnancy is suspected. Ultrasound can also help determine a molar pregnancy. When doing an ultrasound one sees a “snow storm effect” on the screen. Serial hCG levels can show a rapid rise in hCG that may indicate that further study is needed.


There are a few treatments for a molar pregnancy. If the pregnancy has not ended on its own, a suction D&C is usually used to evacuate the mole from the uterus. Induction of labor is not recommended due to increased risks of hemorrhage.

Ongoing treatment includes testing hCG levels several times a week, then weekly, until they are “normal” for three weeks. Then you will be tested monthly for six months, and every two months until a total of one year has passed. Pelvic exams should be done too. A rising level of hCG and an enlarging uterus could indicate a choriocarcinoma, a rarer form of molar pregnancy, which is malignant.

Pregnancy should be avoided for the period of one year. Any method of birth control, with the exception of an intrauterine device, is acceptable.

Losing a pregnancy at any stage can be hard. This means that there will have to be a healing time for all involved, and you'll likely experience the stages of grief, though not necessarily in order or at the same time as your partner. What makes this type of loss different from a “normal miscarriage” or loss is the added concern of the mother's continued health, including the risk of cancer.


Throughout the United States the incidence of a molar pregnancy is about 1 in 1,000, and in Europe it is 1 in 2,000 pregnancies. Molar pregnancy is much more common in areas such as Southeast Asia and Mexico. It is also more common in teens, women over forty, and those who have used the drug Clomiphene (Clomid). There is a 1–2 percent reoccurrence rate for molar pregnancy.

Researchers still do not know exactly why a molar pregnancy occurs. It is believed to be deficiency in certain nutrients, such as protein or carotene. It can also be caused by an ovular (ovulation) defect.

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