Molar pregnancy 
by Peg Plumbo, CNM

Q: We have had three failed pregnancies. The first one was a miscarriage, the next two have been diagnosed as having molar changes related to hydatidiform mole or trophoblastic disease. We are getting conflicting guidance on several issues. How long should we wait before trying again? Should we get tested, and if so, for what? Should we go to a fertility specialist or a high risk OB/GYN?

A: A molar pregnancy is somewhat uncommon, but not rare. In the U.S. it occurs in about 1 in 1000 to 1 in 1500 pregnancies. It occurs predominantly in older women. The chance of recurrence increases with each affected pregnancy (risk for subsequent molar pregnancy is 1 to 2% and the risk of a third after two is about 25%). Learn the signs and symptoms of molar pregnancy.

Hydatiform Mole is one type of gestational trophoblastic disease. In some cases, there may be an embryo in addition (partial molar pregnancy) or there may have never been an embryo or fetus at all. This conception then does not result in the orderly course of events, which produce embryonic tissue organization, but instead the early products of conception (the chorionic villi) are converted into a mass of clear vesicles and these continue to grow and fill up the uterus. The uterus grows quickly making the size almost always larger than dates would indicate and extreme nausea may be present. There are no fetal heart tones and often bleeding and cramping occur.

This is most always the result of the sperm penetrating the egg, which then goes on to duplicate its own chromosomes. The chromosomes of the ova are either absent or inactivated. When there is a partial mole and an embryo is present also, the fetus is often non-viable with chromosomal abnormalities but some do survive.

Following evacuation of the molar tissue, weekly beta hCG levels should be drawn until the hCG titer is within normal limits for three weeks. The titers are then observed at monthly intervals for 6 to 12 months. This is to rule out the possibility of developing choriocarcinoma, a rare malignancy which can occur afterwards.

I personally feel that the best person to treat couples with recurrent molar pregnancies is a perinatologist. These docs are board certified in perinatology, the study and care of problem pregnancies. They often work with a team that includes an ultrasonographer, specialized lab technicians, a geneticist and a nurse specialist. He or she would conduct a very thorough history and physical, review any reports from previous exams, labs and decide if you needed any additional testing.

The time interval between pregnancies depends upon factors such as: type of molar pregnancy, hCG level return to baseline, age of the mother and fertility status. I would hope that your emotional needs as a couple would be discussed and taken into consideration as well.

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