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What is a molar pregnancy?

A molar pregnancy is when tissue in the uterus (womb) forms into an abnormal growth or tumor instead of the placenta. In a healthy pregnancy, the placenta grows in your uterus and supplies your baby with food and oxygen through the umbilical cord. A molar pregnancy always ends in pregnancy loss. Without treatment, it can be life-threatening to a pregnant woman.

Signs and symptoms of a molar pregnancy include:
  • Bleeding from the vagina in the first 3 months of pregnancy
  • Grape-like cysts (fluid-filled sacs) passing out of the vagina
  • Intense nausea and throwing up
  • Pelvic pressure or pain. These happens rarely.
If you have any of these signs or symptoms, call your healthcare provider right away. Learn more at: marchofdimes.org

A molar pregnancy or a hydatiform mole is a rare mass or the growth of tissue inside the uterus that mimics early pregnancy, but there is no embryo present. It is a form of  gestational trophoblastic disease (GTD). A hydatiform mole, or molar pregnancy, results from over-production of the tissue that is supposed to develop into the placenta, that is the trophoblasts. Molar pregnancies are thought to be due to a problem during fertilization. While the exact cause of fertilization problems are unknown, a diet low in protein, animal fat, and vitamin A may play a role.

A molar pregnancy, also called gestational trophoblastic disease, is not always a true pregnancy. If there is a fetus, there are usually abnormalities not compatible with life outside the uterus. It involves excess growth of tissues related to pregnancy. It is frequently suspected by the provider when the size of the uterus is larger than expected based on the expected due date, there is dark brown bleeding, and the level of the hormone HCG is elevated. An ultrasound will diagnose the problem with a "snowstorm" pattern seen rather than a normally developing fetus. Surgery is needed to remove the tissue growths. Following surgery, lab work will be needed weekly until the HCG levels drop to normal and then every two weeks for three months, then monthly for 6 - 12 months. Additional tests might be ordered by the provider as well. It is recommended that a woman avoid pregnancy for one year in order to allow accurate follow-up of the HCG hormone.

Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)
Severe nausea during pregnancy isn't just associated with morning sickness. Severe nausea can also be a sign of something called a molar pregnancy. This occurs when the chorionic villi swell and keep functioning as if there were a fetus—even when there is no viable fetus. A molar pregnancy (which can spread beyond the uterus like a cancer and also cause heavy bleeding) can be detected by an ultrasound and treated with a small surgical procedure called a D&C (dilation and curettage) to remove the excess tissue from the uterus.
YOU: Having a Baby: The Owner's Manual to a Happy and Healthy Pregnancy

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YOU: Having a Baby: The Owner's Manual to a Happy and Healthy Pregnancy

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.