What exactly is a molar pregnancy and what is the experience actually like? Here's insight from experts, real women, and the latest research on this abnormal pregnancy that happens in 1 in 1,000 cases.
illustration of molar pregnancy
Credit: Compilation by Parents Staff; Olena Troshchak—Getty Images (1)

Despite the many real conversations out there surrounding pregnancy—infertility, miscarriage, or high-risk complications—there's one important topic that doesn't get as much limelight: molar pregnancy.

Also called a hydatidiform mole (HM), a molar pregnancy is—in short—a rare mass that grows inside your uterus at the beginning of a pregnancy, according to the U.S. National Library of Medicine. It ultimately results in an unviable pregnancy.

Allison Lemons, a 26-year-old from Erlanger, Kentucky, who recently suffered a molar pregnancy says that before she found out she had one, she had never heard the term before. "This entire process has been overwhelming and full of information," she says.

Recently, stories like Lemons' have gone viral, including that of Michelle Velez, a 38-year-old news anchor from Las Vegas who found out she had a molar pregnancy that turned into stage 4 gestational trophoblastic neoplasia, a rare form of cancer caused by an invasive mole. Now, each story is spreading awareness about molar pregnancy, which occurs in about 1 in 1,000 pregnancies, according to The Mayo Clinic. Here's what every woman should know.

What Is a Molar Pregnancy?

"A molar pregnancy is an abnormal pregnancy that will not develop as a normal viable pregnancy will," explains Roberto Vargas, M.D., an ob-gyn at The Cleveland Clinic. There are two forms of molar pregnancy—partial molar pregnancy and complete molar pregnancy.

Partial molar pregnancy occurs when a sperm divides a little bit too early during the fertilization process, says Dr. Vargas. "It is when there is triploidy, which means there are 69 chromosomes rather than 46 in a normal embryo. This is results from sperm with 46 chromosomes or two sperm, which is not compatible with living," explains Daniel Roshan, M.D., a maternal-fetal medicine specialist at NYU Langone. In a partial molar pregnancy, there is an abnormal placenta and some fetal development.

In Lemons' case, she suffered a miscarriage that turned out to be a partial molar pregnancy. "I am still learning how to cope and process this," she says. "One minute you're seeing your child move around on an ultrasound screen and hearing a strong heartbeat, the next you're being told your child has passed and you might develop cancer. That's a load."

A complete molar pregnancy happens when there is an abnormal placenta and no fetus. A complete mole, as doctors call it, happens when the egg doesn't carry any genetic materials and two sperm fertilize one egg, explains Dr. Roshan.

In the case of a molar pregnancy, an ultrasound might show no embryo at all but grape-like material covering the uterus, says Dr. Roshan. With partial moles, you might see fetal parts, Dr. Vargas says.

In about 15 to 20 percent of complete molar pregnancies and up to 5 percent of partial molar pregnancies, the mass of a molar pregnancy can spread to nearby tissues (which is called an invasive mole). In rarer cases, it can go on to become a cancerous tumor called choriocarcinoma.

As for their cause? Most molar pregnancies are random. They usually happen in people younger than 18 or older than 45, but they can happen in women of any age, says Dr. Vargas.

Molar Pregnancy Symptoms

The most common symptom associated with molar pregnancy is bleeding early in the pregnancy, says Dr. Vargas, who notes that is then corroborated by an abnormal ultrasound. Of course, not all women experience bleeding.

If a molar pregnancy is not detected early (today, with the advent of better ultrasound technology, "abnormal" pregnancies are often spotted early), someone might also experience severe nausea, vomiting, have issues with high blood pressure, or have a pregnancy where they feel larger than their pregnancy date suggests, says Dr. Vargas.

With molar pregnancy, levels of human chorionic gonadotropin (hCG) are often very high, notes Dr. Roshan. This was the case for Velez, who, at about nine weeks pregnant had hCG levels that were so high they would have been as if she were carrying five or six babies, she explains. She says she also felt extremely nauseous, sicker than she thought was normal, not knowing this could be a sign that something more serious was going on.

Treatment for Molar Pregnancy

First, molar pregnancy diagnosis and treatment can be incredibly emotional. In part, that's because treatment is dilatation and curettage (D&C), a surgical procedure that removes tissue from inside your uterus, but also because after a D&C and confirmed molar pregnancy, your doctor will monitor your levels of hCG until they drop back to zero, says Dr. Roshan. hCG rises or plateaus can signal a regrowth of tissue and a potential risk for cancer. You'll be checked in certain intervals for a year, says Dr. Roshan.

This can be incredibly stressful and upsetting. "There are no words to describe the fear and anxiety that come with blood draws. You are constantly worried about your numbers, always hoping there isn't a rise. It consumes you. It's a hopeless feeling," says Lemons.

Velez notes that monitoring the progress of hCG levels can feel like a "never-ending miscarriage" and an "emotional mind game" as usually, with pregnancy, you want hCG levels to rise but after a molar pregnancy, you want them to go down. "That's all you're focused on for as long as it takes," she says.

In Velez's case, after levels of hCG initially dropped after her D&C, her numbers started creeping up, which led to her being diagnosed with cancer. Currently, she's undergoing multiple rounds of chemotherapy, noting that her cancer is treatable.

Conceiving After a Molar Pregnancy

If you're younger than 35, doctors generally suggest waiting a year after hormone levels return to normal to begin "trying again" and if you're older than 35, waiting at least six months to conceive so that doctors can confirm that the molar pregnancy is gone.

"I think the most important thing for women who have molar pregnancies to know is that they should expect normally developing subsequent pregnancies," says Dr. Vargas. While the risk of a repeat molar pregnancy does increase (from less than a 1 percent risk to 1 to 2 percent risk), it is still small. "Overall, there's a really high probability of having a normal viable pregnancy after the molar pregnancy," says Dr. Vargas.

Lemons notes that she is looking forward to being cleared from her doctor to start trying again—hopefully in February.

Support and Molar Pregnancy Awareness

For women who have gone through molar pregnancies, finding support from friends, family members, and other women who have experienced them is often key—but that often requires making the problem more well-known.

"It bothers me that there's something that's this common that no one knows about," says Velez. "I want people to know everything about molar pregnancy. What's so scary is that it resembles and mimics a pregnancy so closely."

She says that while utterly devastating, posting publicly about her cancer diagnosis connected her to people all over the world. "That was the best thing that could have ever happened," she says. "I felt like I was the only one who was going through this. I had no one to talk to and I didn't know molar pregnancies were as common as they are."

Lemons notes that speaking about the baby she lost and molar pregnancies has helped her heal. "Finding other families who have shared this experience has brought a level of comfort and peace. Sharing my story has brought many new relationships for me."

Something else that sharing her story helped Velez with? "Most people who get a cancer diagnosis have this question of 'why me?' That's a question that you cannot answer," she says. "But being able to share my journey and connect with others has given me a partial answer."

If you or someone you know is looking for support, both Lemons and Velez point to resources including Facebook groups (My Molar Pregnancy) that connect women who have experienced molar pregnancies.