What is a molar pregnancy?

A molar pregnancy is a pregnancy that is not developing in a manner that facilitates the birth of a baby. Instead of the usual 46 chromosomes in a fetus (23 chromosomes each from both parents), molar pregnancies result in a pregnancy that has an abnormal number of chromosomes. Molar pregnancies can either be complete or partial, and involve the growth of a fetus or not. However, in no case can such a pregnancy result in the birth of a baby.

Complete molar pregnancies involve a fertilized egg with two sets of identical chromosomes from the father, and none from the mother. In this case, an embryo, placenta, and amniotic sack are not able to grow at all. Instead, a cyst-like structure of cells forms something that can be detected through a routine ultrasound. In partial molar pregnancies, 23 chromosomes come from the mother, but normally two sets of chromosomes come from the father, making a total of 69. These pregnancies can result in the growth of a placenta and an embryo, but the embryo will not be able to survive.

Molar pregnancies are classified as tumors, but even though they sometimes grow even outside of the uterus, they are not normally cancerous. The resulting growths can usually be removed without complication. Molar pregnancies are fortunately a rare occurrence. They happen in around one in a thousand pregnancies. Risk factors for a molar pregnancy include a mother being over 40, a history of miscarriages or molar pregnancies, or a lack of Vitamin A.

Finding out about a molar pregnancy can be a big shock to expectant couples. The grieving process is much the same as it is for any other type of pregnancy loss, and women who have suffered a molar pregnancy may wonder if they will ever have a healthy baby in addition to grieving their lost pregnancy. Talk to your doctor about any concerns you have in this area, and seek counseling if you feel the need. Readers may also like to look at What is a missed miscarriage?