Molar pregnancy risk factors

A molar pregnancy develops when fertilisation produces abnormal placental tissue instead of a normally developing pregnancy. It can occur without any identifiable risk factor. A previous molar pregnancy is a recognised reason for closer review in a later pregnancy. Age at pregnancy and certain reproductive histories may also influence clinical concern, but they do not diagnose the condition.

Risk factors are not a prediction that a person has cancer or will develop it. Some molar pregnancies remain limited to the uterus; others need specialist assessment because abnormal trophoblastic tissue can persist after treatment.

Tell your obstetrician or gynaecologist about any previous molar pregnancy, unusual bleeding, severe nausea, or a uterus that seems larger than expected for the pregnancy stage. Assessment may include an ultrasound, blood testing for human chorionic gonadotropin, and a pelvic examination. If a molar pregnancy is confirmed, follow-up blood tests help show whether the abnormal tissue is resolving.

Keep every follow-up appointment and ask which symptoms should prompt a call. Treatment can involve removal of the abnormal tissue; persistent disease may be treated with [Chemotherapy](/treatments/systemic-therapy/chemotherapy/).

Seek urgent medical care for heavy vaginal bleeding, faintness, severe pelvic pain, trouble breathing, or vomiting that prevents fluids from staying down. Contact your maternity team promptly for any new bleeding in pregnancy; [Bleeding Between Periods](/symptoms/bleeding-between-periods/) is a separate symptom topic, but bleeding during pregnancy needs pregnancy-specific assessment.

Ask whether your history changes the ultrasound plan, which blood-test results need repeating, how long monitoring may continue, and when it is medically appropriate to try for another pregnancy.