Molar Pregnancy

Pregnant woman holding teddy bear
Jamie Grill/Getty Images

A molar pregnancy refers to a pregnancy that is a type of gestational trophoblastic disease (GTD). It can refer to either a complete or a partial mole. While there are regional differences, the rate of molar pregnancy is about 1/1000 to 1/1500. We still do not know exactly why a molar pregnancy occurs. It is believed to be a nutritional deficit, like protein or carotene. It can also be caused by an ovular (ovulation) defect.

Women at Risk

  • Over 50 years
  • Clomiphene stimulation (Clomid)
  • 1-2% chance of a second mole
  • Early Teens

Complete Mole

This 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.

Partial Mole

This 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. Rarely, a partial mole will exist with twin pregnancy, however, the other twin rarely survives.


Symptoms include:

  • Increased nausea and vomiting
  • Vaginal bleeding
  • Increased hCG levels
  • Rapidly growing uterus
  • Pregnancy induced hypertension prior to 24 weeks
  • No fetal movement or heart tone detected
  • Hyperthyroidism
  • Pulmonary Embolism


Most of the time a molar pregnancy will spontaneously end.

When the woman passes tissues that appear to be grape like 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.


If the pregnancy has not ended on its own a suction D & C is usually used to evacuate the mole form the uterus. If a woman does not wish to continue with childbearing sometimes a hysterectomy is offered. Induction of labor is not recommended due to increased risks of hemorrhage.

On going treatment includes hCG levels to be taken 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, an uncommon but treatable form of cancer associated with pregnancy. This occurs in about 1/40,000 cases.

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

If you are Rh negative, then you will also receive the Rhogam shot.

Gestational Trophoblastic Disease (GTD) & Neoplasia (GTN)

This encompasses a range of problems that arise from a placental trophoblast. GTN refers to persistent tissue found in follow-up to a molar pregnancy that is assumed to be malignant.

GTN is one of the most curable cancers in the gynecology. This is a change from earlier years because of the increased number of treatments, personalized care, it's more easily detected, and its extremely sensitive to chemotherapy.

There are two groups, nonmetastatic and metastatic, meaning the disease has spread to other parts of the body, most frequently the liver and the brain. If you do not have brain or liver involvement your chances of recovery are nearly 100%, you are in the low-risk group. Metastasis in either of the two areas indicates that you are in the high-risk group.

Only 15-30% of women with a molar pregnancy will need further treatment. The main sign that this might be necessary would be continued bleeding after a D & C. Although other signs include abdominal pain, ovarian enlargement, and signs of a metastasis include pulmonary symptoms (coughing, etc.).

Methotrexate can also be used to help excavate the uterus. (This is an injection that causes the tissues to die and be discharged from the vagina.)

Emotional Health

Losing a pregnancy at any stage can be hard, and even when there may technically be no baby to grieve due to the reactions of the cells involved. This means that there will have to be a healing time for all involved and the stages of grief will be experienced, 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 that you have the added concern of the mother's continued health, including the risk of cancer.

While the risks of a molar pregnancy repeating itself are very small, it is something that most couples will think about prior to conceiving again.

The time to wait for another conception is also longer than a standard waiting time after a miscarriage. This can add pressure and heart ache.

Counseling, support groups, journaling, anything you can do to get your emotions out are great. Look for local resources as well as resources online.

Attempting Pregnancy Again

Do you or don't you? This is not an easy question.

If you've previously had a molar pregnancy without complications, your risk of having another molar pregnancy are about 1-2%. These odds are less than having a second ectopic pregnancy (7-25%), so in that respect the answer is good.

Medically it will depend on many factors. So couples will choose to have genetic counseling prior to conceiving again. In the end, it's up to you and your partner if you wish to try again.


Choriocarcinoma. Pub Med Health. 2010.

Obstetrics: Normal and Problem Pregnancies. Gabbe, S, Niebyl, J, Simpson, JL. Fifth Edition. 2007

OB/GYN Secrets, 2nd Edition. Frederickson,HL & Wilkins-Haug, L. 1997.

Continue Reading