A molar pregnancy (medically referred to as a hydatidiform mole) is a devastating and rare condition that occurs in 1 out of every 1,000 pregnancies. A molar pregnancy occurs early in the first trimester, when the tissue that would have grown into an embryo (and later your future baby) becomes a noncancerous (benign) tumor in your womb.
Molar pregnancies are a type of gestational trophoblastic disease (GTD) – a group of tumors that develop inside a woman’s uterus. A majority of GTDs are non-cancerous, and these don’t spread into deep body tissues or invade other parts of the body. There are a few GTDs that are cancerous.
Causes of a Molar Pregnancy
There is nothing you could have done to prevent a molar pregnancy.
Molar pregnancies develop randomly when there are errors during the fertilization process. Sometimes, two sperm fertilize one egg, and this can grow into an abnormal fetus and placenta. Other times, a sperm fertilizes an egg that contains no genetic material.
Although molar pregnancies are rare, things that can increase your risk of this complication include the following:
- Age – You are under 20, or over 35 when you get pregnant.
- History of Miscarriages – You’ve had two or more miscarriages in the past.
- Past Molar Pregnancy – You are at higher risk for a molar pregnancy if you’ve experienced one in the past. One out of every 100 women with a previous molar pregnancy will experience another one.
- Ethnicity – For some reason, women of Southeast Asian descent are at higher risk.
- Lack of Carotene in Diet – Carotene is a type of vitamin A. Research has shown that women who don’t get enough carotene or vitamin A in their diet have a higher rate of having a complete molar pregnancy.
Types of Molar Pregnancies
There are two types of molar pregnancies:
- Partial Molar Pregnancy – With a partial molar pregnancy, two sperm fertilized one egg. When this happens, there’s an abnormal placenta and some fetal tissue. If you have a partial mole with a fetus present, the fetus has severe genetic problems and will not be able to survive.
- Complete Molar Pregnancy – If you have a complete mole, a sperm fertilized an egg with a lost or inactivated nucleus. As a result, the egg has no genetic information. The sperm duplicates itself, but no fetus develops. The tissue grows and can fill up the uterus.
In very rare cases, you may have a twin pregnancy, but one of the twins is a regular developing baby, and the other is a molar pregnancy.
HCG Levels in Molar Pregnancy
Extremely high levels of hCG in your urine or blood are one sign that you may have a molar pregnancy.
In a normal, healthy pregnancy, the placenta secretes human chorionic gonadotrophin (hCG) into the bloodstream to help support the pregnancy. When you have a molar pregnancy, there is an overgrowth of placental tissues. As a result, you will have higher levels of hCG in your blood.
Symptoms of a Molar Pregnancy
Even though molar pregnancies are not true pregnancies (since no viable embryo is involved), they do trigger the symptoms and early signs of pregnancy – such as morning sickness and a missed period.
Other molar pregnancy symptoms to be on the lookout for include:
- Severe Nausea and Vomiting – Because of the very high levels of hCG associated with molar pregnancies, women with this complication often experience severe morning sickness. Sometimes, the nausea and vomiting is so intense that women have to be hospitalized.
- Vaginal Bleeding – Women with ectopic pregnancies will have spotting in the first trimester. At first, they may have brownish-colored discharge, or bright red spotting. Your vaginal spotting can be intermittent or continuous. Sometimes, this vaginal bleeding will start at 6 weeks pregnant, or it can start in the final weeks of your first trimester.
- Uterus Size Abnormality – Women with a complete molar pregnancy will have a uterus that is larger than expected for that stage of pregnancy. If you have a partial mole, your uterus will be smaller than expected for your gestational age.
- Abdominal Cramping – In a molar pregnancy, the placenta forms a mass of cysts. It’s common to experience abdominal cramping and pain because from the growth of these cysts.
- Abdominal Swelling – Your abdomen may swell when you have a molar pregnancy, because the uterus is growing much faster than normal, due to the increasing number of cysts forming.
- Vaginal Discharge of Grape-Shaped Tissue – If you are noticing clumps of tissue that looks like a cluster of grapes, this is a sign that you are having a molar pregnancy.
- Preeclampsia Before 20 Weeks Pregnant – Early preeclampsia, which is a severe form of high blood pressure in pregnancy, can be a sign of a molar pregnancy. In a pregnancy that involves a true baby, preeclampsia does not occur until 20 weeks pregnant. It is almost guaranteed that you have a molar pregnancy if you start having signs of preeclampsia before 20 weeks of pregnancy – like hypertension, vision changes (blurry vision), severe headaches, and swelling in your legs, ankles, and feet.
- Hyperthyroidism – Women with molar pregnancies will display signs of hyperthyroidism (overactive thyroid). Molar pregnancies release chemicals that stimulate the thyroid gland, so women with this complication can start to experience common hypothyroidism symptoms – including rapid heart rate, restlessness, loose stools, skin that is warmer and more moist than normal, trembling hands, unexplained weight loss, and heat intolerance.
If you have any of these symptoms, contact your healthcare provider immediately.
Molar pregnancies are diagnosed using a pelvic ultrasound, blood tests to measure the level of hCG, and a pelvic exam.
Treatment of Molar Pregnancy
After diagnosis, molar pregnancies need to be treated immediately. If the tumor is not removed, it can lead to gestational trophoblastic disease (GTD). In rare cases, GTD can progress to cancer.
To treat a molar pregnancy, the molar tissue needs to be removed from your uterus with an outpatient procedure called dilation and curettage (D&C).
During a D &C procedure, you will receive anesthesia. A speculum will be inserted into your vagina, similar to a Pap smear. The physician will dilate the cervix and use a vacuum to suction/remove the molar tissue from your uterus. The remaining tissue will be gently scraped from your uterine wall.
Afterwards, you may have a chest X-ray to see if any cells from the molar tissue spread to your lungs. Although it’s rare for a molar pregnancy to spread elsewhere in the body, when it does spread, the lungs are the most common targets.
For many months after your D & C, your healthcare provider will take blood samples to measure your hCG levels to make sure that they are decreasing. If they are not going down, this may be a sign that there is still molar tissue growing in your uterus. Even after your hCG levels go down to zero, you still need regular blood tests (about every one to two months) to check for hCG.
Sometimes, abnormal molar tissues remain in the uterus after your D & C. This occurs in 11 percent of all partial molar pregnancies and between 18 and 29 percent of complete molar pregnancies. In these situations, you will have chemotherapy to get rid of the abnormal molar tissue.
Chemotherapy is successful in a majority of cases. However, in a small number of cases, the molar tissue will become an advanced, malignant cancer called gestational choriocarcinoma.
- Although cancer is scary, when the choriocarcinoma has not spread outside of the uterus, the cure rate is 100 percent. When the cancer spreads to other parts of the body, you still have an 80 to 90 percent chance of survival.
If you don’t plan on having any more children, or if the molar pregnancy is very advanced, you can have a hysterectomy as a treatment option.
Pregnancy After Molar Pregnancy
Although it is devastating to have a molar pregnancy, you can have normal pregnancies in the future. Your risk of having a repeat molar pregnancy is between 1 to 3 percent, so it is rather low.
Even after D & C, or chemotherapy, you have a good chance of having a normal pregnancy in the future. The good news is that you are not at increased risk for any complications – such as preterm labor, stillbirths, or birth defects. However, you will need to have a first trimester ultrasound to ensure that everything is proceeding normally.
It is a good idea to wait at least 12 months (or one year) before you try to get pregnant again. You need to wait this long, because you need a year of having zero hCG levels to ensure that there is no molar tissue remaining.
After a molar pregnancy, it is normal to feel devastated and grieved. Counseling and support groups may be an excellent way for you to cope.