Gestational Mole: When Pregnancy Becomes Cancer

What Is a Gestational Mole?

A gestational mole (molar pregnancy) is a benign tumor that arises from a fertilization error. In an incomplete mole, one sperm with duplicated DNA — or two sperm — fertilizes a normal egg, producing an imperfect placenta alongside an embryo with genetic anomalies incompatible with life. In a complete mole, a DNA-free egg is fertilized by the same types of sperm, creating only an abnormal placenta with no embryo at all.

Can a Molar Pregnancy Turn Into Cancer?

Yes — and that is the most serious risk. When molar cells implant in the uterine wall, placental cancer (gestational trophoblastic neoplasia) can develop. This affects fewer than 5% of women with a partial mole, but as many as one in five women with a complete mole. In aggressive cases, metastasis — mainly to the lungs — is possible.

How Common Is It in Brazil?

According to Professor Antônio Braga, an obstetrics specialist at the Federal University of Rio de Janeiro (UFRJ) who coordinates one of the world's leading molar pregnancy clinics, one in every 200 to 400 pregnant women in Brazil will develop the disease. That rate is significantly higher than in the United States (1 in 1,000) or the United Kingdom (1 in 2,000). Researchers suspect genetic, immunological and dietary factors, but nothing has been conclusively established yet.

How Is It Diagnosed?

Most patients discover the condition the same way occupational therapist Daiana Nascimento did: through a routine ultrasound after a positive blood or urine pregnancy test. In Daiana's case, within less than a month of her happiest day she was dealing with placental cancer — a reality she says she never imagined possible.

Why Must the Mole Be Removed Immediately?

Leaving a mole in place risks uterine bleeding, thyroid disruption and dangerous changes in blood pressure. Prompt removal is essential regardless of whether the mole is complete or incomplete.