What should you know about molar pregnancy and the fetus?

A molar pregnancy, also called a hydatidiform mole, starts when an abnormal fertilisation event causes placental cells to grow in an unusual way. In a complete mole, there is no developing embryo. In a partial mole, some fetal tissue may be present, but it cannot develop into a viable fetus. The abnormal tissue can make pregnancy hormones rise and may appear as unusual tissue on an ultrasound. A molar pregnancy is not caused by anything the pregnant person did.

Most molar pregnancies are not cancer, but some abnormal trophoblastic cells can remain after the pregnancy is removed and need treatment. Rarely, gestational trophoblastic disease can become a cancer such as choriocarcinoma. Follow-up hormone testing helps the care team check that the abnormal cells have cleared.

Arrange care with an obstetric or gynaecology team experienced in molar pregnancy. Assessment commonly includes an ultrasound, blood tests for the pregnancy hormone hCG, and sometimes examination of tissue removed from the uterus. Treatment usually removes the molar tissue from the uterus. Your clinician will explain the safest approach for your symptoms, bleeding, medical history, and future pregnancy plans.

Keep every follow-up appointment for hCG testing. The result should steadily fall; a plateau, rise, or persistent detectable level can signal remaining trophoblastic disease and may lead to additional treatment. Use contraception if your team recommends it during monitoring, because a new pregnancy can make hCG results difficult to interpret.

Seek urgent medical help for heavy or increasing vaginal bleeding, faintness, severe weakness, severe pelvic or abdominal pain, trouble breathing, chest pain, or a severe headache with visual changes. Bleeding between periods can also need assessment during recovery, especially if it is new, persistent, or accompanied by pain or dizziness.

Contact your care team promptly if follow-up hCG results stop falling, rise, or remain detectable, or if symptoms return after treatment. These findings do not identify the cause by themselves, but they require timely review.

Ask whether the findings suggest a complete or partial mole, how the tissue will be removed, and when your hCG monitoring begins. You can also ask what symptoms should trigger emergency care, how long monitoring is expected to continue, when it is medically reasonable to plan another pregnancy, and whether a specialist oncology team should be involved. If hCG remains elevated, ask what further tests or treatments may be considered, including chemotherapy.