Molar Pregnancy – Symptoms and Causes
Overview
Molar pregnancy is an uncommon pregnancy complication. It affects the cells called trophoblasts, which normally develop into the placenta. There are two distinct types of this condition.
In complete molar pregnancy, placental tissue becomes swollen and develops what appear to be fluid-filled cysts. No fetus forms in this type.
With partial molar pregnancy, the placenta contains both normal and abnormal tissue. While a fetus may develop, it cannot survive and is typically miscarried early in pregnancy.
This condition requires prompt medical attention because it can lead to serious complications, including a rare form of cancer. Early treatment is essential to protect the mother’s health.
Symptoms
Molar pregnancies often start like normal pregnancies but soon develop distinct symptoms.
In the first trimester, you might notice:
- Dark brown or bright red vaginal bleeding
- Extreme nausea and vomiting beyond typical morning sickness
- Grape-like cysts passed through the vagina
- Pain or pressure in the pelvic area
Modern detection methods help identify most molar pregnancies early. However, if not caught in the first three months, additional symptoms may develop:
- Unusually rapid growth of the uterus
- Preeclampsia (high blood pressure with protein in urine) before week 20
- Cysts on the ovaries
- Hyperthyroidism (overactive thyroid gland)
These symptoms require prompt medical attention. Your healthcare provider can perform tests to confirm a diagnosis and discuss appropriate treatment options.
Causes
A molar pregnancy happens when an egg gets fertilized in an unusual way. Normally, human cells have 23 pairs of chromosomes with one chromosome in each pair coming from each parent.
In a complete molar pregnancy, something goes wrong during fertilization. The egg gets fertilized by one or two sperm, but the mother’s chromosomes are either missing or not working properly.
Instead, the father’s chromosomes get duplicated, and there are none from the mother.
For partial or incomplete molar pregnancies, the mother’s chromosomes are present, but there are two sets of chromosomes from the father. This creates an embryo with 69 chromosomes instead of the normal 46.
This typically happens when two sperm fertilize the same egg at once, creating an extra set of the father’s genetic material. These chromosome abnormalities prevent the fertilized egg from developing into a healthy embryo and placenta.
Risk Factors
Several factors may raise your chance of having a molar pregnancy:
Previous Molar Pregnancy: If you’ve had this condition before, you face a higher risk of it happening again. About 1 in 100 people who had a molar pregnancy will experience another one.
Maternal Age: Your age plays a role in risk. Women younger than 15 or older than 43 have an increased chance of developing a molar pregnancy.
Complications
After treatment for a molar pregnancy, some patients may experience persistent gestational trophoblastic neoplasia (GTN). This happens when molar tissue remains and continues to grow in the body.
Persistent GTN occurs more frequently in complete molar pregnancies than partial ones. Doctors can detect this condition through elevated human chorionic gonadotropin (HCG) levels after the initial molar tissue removal.
In some cases, the abnormal tissue invades the middle layer of the uterine wall, causing vaginal bleeding.
Treatment options for persistent GTN include:
- Chemotherapy (most common approach)
- Hysterectomy (surgical removal of the uterus)
In rare situations, a more serious condition called choriocarcinoma may develop. This cancerous form of GTN can spread to other organs throughout the body.
Complete molar pregnancies carry a higher risk of choriocarcinoma than partial molar pregnancies. Despite its severity, choriocarcinoma typically responds well to chemotherapy treatment.
Prevention
After experiencing a molar pregnancy, consult your healthcare provider before trying to conceive again. Waiting six months to one year is generally recommended.
The chance of having another molar pregnancy remains low, but it is slightly higher for those who have previously had one.
Healthcare providers will likely perform early ultrasound examinations during future pregnancies. These scans help monitor your condition and confirm that the baby is developing normally.
