Molar Pregnancy

Definition - What does Molar Pregnancy mean?

A molar pregnancy occurs when a fertilized egg fails to develop into an embryo and instead becomes an abnormal tissue growth. This is the result of excess production of tissue that is supposed to form the placenta. This condition is a type of pregnancy loss, and may require treatment to address. Molar pregnancy is caused by a genetic dysfunction, which may impact future pregnancies.

A molar pregnancy may also be referred to as a hydatidiform mole.

FertilitySmarts explains Molar Pregnancy

There are two types of molar pregnancies, complete molar pregnancy and partial molar pregnancy.

Complete molar pregnancy: the sperm fertilizes an empty egg, and as a result a placenta grows despite a lack of embryo. The body produces the pregnancy hormone, hCG, but no fetus forms.

Partial molar pregnancy: an embryo and an abnormal mass form. However, the embryo has severe birth defects. The fetus is not viable, and cannot live when paired with the abnormal tissue mass.

Symptoms of a molar pregnancy include:

  • Vaginal bleeding
  • Early preeclampsia
  • High hCG levels
  • Lack of fetal movement or heart tone

If these symptoms are present, additional testing may be performed. An ultrasound exam may show the fetus appears similar to a “cluster of grapes,” indicating the placenta is deformed and a molar pregnancy is occurring.

Molar pregnancies will end in spontaneous abortion (miscarriage). If identified prior to miscarriage, a dilation and curettage (D&C) procedure may be performed to remove the mole.

The majority of women treated for molar pregnancy face no additional treatment. However, there is an increased risk of future complications. Follow up appointments for six months are standard and it is advised women delay another attempt at conception for one year as there is an a high risk of an additional molar pregnancy during this time frame. Genetic counseling may be advised for couples who plan to attempt another pregnancy.

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