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Risk factors

Although the exact cause of gestational trophoblastic disease is unknown, it has been linked to certain risk factors.

A risk factor is anything that increases your chances of getting a disease. Having a risk factor does not mean that you will get gestational trophoblastic disease, and not having risk factors does not mean that you won’t get gestational trophoblastic disease. If you think you may be at risk of gestational trophoblastic disease, you should discuss this with your doctor.

Risk factors for gestational trophoblastic disease include:

  • Age: Women under 20 and over 40 years are at higher risk.
  • Previous gestational trophoblastic disease: For women who have had a hydatidiform mole in the past, the chance of it occurring again is about one per cent.


Gestational trophoblastic disease is not always easy to find. In its early stages, a hydatidiform mole may look like a normal pregnancy.

You should see a doctor if:

  • you have vaginal bleeding (not menstrual bleeding)
  • you are pregnant and the baby has not moved at the expected time
  • you have extremely severe morning sickness (this is caused by unusually high levels of the hormone, human chorionic gonadotrophin or hCG).

Vaginal bleeding can also be a symptom of gestational trophoblastic neoplasia or placental-site trophoblastic tumour. These tumours can occur after a hydatidiform mole, after an abortion or after a normal pregnancy and delivery.

Having these symptoms may not mean you have gestational trophoblastic disease. However, you should be examined by your GP to investigate.

If necessary, your GP will refer you for tests.

Early detection

In many cases, a hydatidiform mole will be detected during routine antenatal care during the first trimester of pregnancy. It may also be detected after a miscarriage.

After a molar pregnancy, your hCG levels will be closely monitored to detect any cells that remain. If the hCG level increases or does not go down to normal, more tests will be done to see whether the tumour has spread.

If a woman is not pregnant and hCG is in the blood, it can be a sign of gestational trophoblastic disease.