Molar Pregnancy

A molar pregnancy is a pregnancy complication that occurs in 1 out of every 1,000 pregnancies in the U.K. It occurs when there is a problem with the embryo due to the sperm and egg. As a result, a malformed placenta, known as a "mole," forms in the uterus.

Clinically known as a hydatiform mole, molar pregnancies can be very frightening experiences. They also pose potential health complications if left untreated. Luckily, effective treatment is available for women suffering from molar pregnancies.

Types of Molar Pregnancies

There are two types of molar pregnancies:

  • Complete Mole: A complete mole occurs when the nucleus of the mother’s egg becomes lost or inactivated during fertilization. As a result, the fertilized egg has none of the mother’s chromosomes. To compensate, the father’s chromosomes are doubled during reproduction, and this prevents a fetus from forming. With a complete mole, abnormal placental tissue (often resembling a cluster of grapes) fills the uterine cavity and no baby ever grows.
  • Partial Mole: A partial mole occurs when two sperm cells fertilize the mother’s egg. This causes an embryo to form with 69 chromosomes, instead of 46. Due to these extra chromosomes, the fetus suffers birth defects and dies in the uterus. With a partial mole, there may be some normal placental tissue and membranes found in the uterus.

What Causes a Molar Pregnancy?

Unfortunately, researchers are still unsure what causes these molar pregnancies to form. It has been theorized that certain ovulatory disorders may contribute to the formation of a molar pregnancy. It has also been theorized that certain nutritional deficiencies, including carotene and protein deficiencies, may contribute to these types of pregnancies.

For more information on the causes of molar pregnancy, visit, a comprehensive molar pregnancy support site that covers all aspects of this particular pregnancy complication, including its effects on fertility, how to cope emotionally and provides a community forum for networking with other sufferers

Who’s At Risk for a Molar Pregnancy

Unfortunately, any woman, no matter what her age, race, or medical background, can develop a molar pregnancy. Certain factors do seem to increase your risk however. These risk factors include:

  • being over the age of 40
  • having a previous molar pregnancy
  • having a previous miscarriage
  • having a previous ectopic pregnancy
  • living in certain geographic locales (especially Southeast Asia and Mexico)

Symptoms of a Molar Pregnancy

Early on, a molar pregnancy is associated with symptoms similar to that of a normal pregnancy, including morning sickness, fatigue and breast tenderness. However, additional symptoms begin to appear around the tenth week of pregnancy, and may include:

  • severe nausea and vomiting
  • vaginal bleeding
  • abdominal pain or cramps
  • high blood pressure (premature preeclampsia)
  • coughing (rarely, coughing up blood)
  • no fetal movement or heartbeat

Diagnosis and Treatment of Molar Pregnancy

Most molar pregnancies end early and are expelled by the body. Those molar pregnancies that do not end can be diagnosed through ultrasound imaging. An ultrasound will reveal the abnormal placental mole, and may also reveal the absence of a fetus. Inordinately high hCG levels can also help to confirm a molar pregnancy.

Treatment involves removing all of the molar tissue from within the uterine cavity. This is typically done using suction curettage under general anesthesia. A small vacuum-like instrument is inserted into the uterus in order to remove all of the mole’s tissues.

If a woman does not plan on bearing any more children, a hysterectomy may also be performed. Frequent hCG testing and pelvic exams will be required for the next year to ensure that the molar pregnancy does not continue growing.

Complications Associated with a Molar Pregnancy

In about 20% of complete moles and 2% of partial moles, there is some molar tissue left inside of the uterus. This molar tissue can continue growing inside of the uterus, leading to abnormal vaginal bleeding and risk of infection. Referred to as gestational trophoblastic neoplasia, this complication is generally signaled by rising hCG levels after suction curettage. Treatment for this includes the drug, methotrexate, which is highly effective at ending the growth of the mole.

Rarely, a gestational trophoblastic neoplasia can become cancerous and invade other organs. In particular, the mole’s cells can begin to grow in the lungs, brain, bones, or vagina. If left untreated this can be a deadly complication. However, using a chemotherapy drug, or a combination of chemotherapy drugs, is almost 100% effective at stopping the spread of the cancer.

Emotions and Molar Pregnancies

As with any pregnancy loss, a molar pregnancy can be extremely devastating for the couple involved. However, it can often be even more difficult to deal with because of the health concerns that the condition can cause for the mother. When you have recovered, it is important to take the time to mourn your loss.

If you find it helpful, you may be interested in pursuing couples therapy, private counseling, or membership in a molar pregnancy support group. Journaling and other personal forms of expression may also help you to come to terms with your loss.

Getting Pregnant Again

You may be especially concerned about becoming pregnant again in the future. However, it is highly unlikely that you will suffer another molar pregnancy. In fact, the chance of experiencing a second molar pregnancy is only about 1 in 100. The vast majority of couples go on to have healthy babies.

With that said, though, it is usually recommended that couples wait at least one year before become pregnant again. This is because your hCG levels need to be continuously monitored at regular intervals for a year after a molar pregnancy. After the mandatory one-year wait, you should receive the all clear from your health care provider and can start trying again.

Learn more about Molar Pregnancies And Miscarriage

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