Molar pregnancy

A molar pregnancy is a rare type of pregnancy loss. It happens when an egg is fertilised but a baby does not develop. Instead, there is an unusual growth of the cells that normally form the placenta.

Molar pregnancies occur more often in:

• women younger than 15 years
• women older than 45 years
• women who have had a molar pregnancy before

A molar pregnancy is also called a 'hydatidiform mole' or 'gestational trophoblastic disease' (GTD).

A pregnancy starts with a sperm fertilising an egg. The fertilised egg travels to the uterus (womb) where it implants. A molar pregnancy occurs when the cells that normally form a placenta grow into a clump of abnormal cells instead.

A molar pregnancy can be complete or partial.

• In a complete molar pregnancy, an embryo does not develop at all. It usually occurs when an egg that does not contain any genetic material is fertilised by a sperm.
• In a partial molar pregnancy, a fetus can develop, but it will be abnormal and cannot survive. A partial molar pregnancy usually develops when a normal egg is fertilised by 2 sperm.

If you have a molar pregnancy, it wasn't caused by anything you did or didn't do.

Women with a molar pregnancy often feel pregnant, and have pregnancy symptoms such as sore breasts and morning sickness.

This is because the pregnancy hormone called human chorionic gonadotropin (hCG) is still made when you have a molar pregnancy. In fact, higher-than-normal amounts of hCG are common with a molar pregnancy. This can cause severe morning sickness.

Other symptoms of a molar pregnancy can include:

• vaginal bleeding
• a dark vaginal discharge

Your doctor or midwife may also notice that your uterus feels larger than it should be for your stage of pregnancy.

Some women with a molar pregnancy may have other problems, including:

• high blood pressure
• pre-eclampsia
• thyroid problems (Opens in new tab)

If you have symptoms that you are concerned about, see your doctor or midwife. They will ask about your symptoms and examine you.

Your doctor may recommend an ultrasound scan and a blood test to check your pregnancy hormone level.

Some women may discover they have a molar pregnancy at their first routine pregnancy ultrasound scan.

Others may find out about a molar pregnancy after a miscarriage or termination, if the pregnancy tissue is examined under a microscope.

A molar pregnancy needs to be removed to avoid complications. This is done in a hospital or clinic by a specialist doctor. You can usually go home on the same day as the procedure.

The specialist doctor will remove the tissue from your uterus. This is done during a procedure called a 'dilatation and curettage' (Opens in new tab) (D&C). A D&C is usually done under general anaesthetic (Opens in new tab).

The cells from the molar pregnancy are tested in a laboratory. Having the tissue removed is enough treatment in most cases of molar pregnancy.

In some cases, some of the molar tissue persists. It can grow deeper into your uterus and spread. This is called an 'invasive mole' and needs further treatment.

Rarely, the molar tissue turns into a cancer called 'choriocarcinoma', which needs more treatment.

Follow-up care

To check that the molar tissue is completely gone, your doctor will ask you to have weekly blood tests. These are to check your hCG level until it returns to normal.

Once your hCG level returns to normal, you will be asked to have monthly blood tests for another 6 months to make sure all is well.

A molar pregnancy does not affect your chances of getting pregnant again. But you will be advised to wait for your doctor's all-clear before trying to get pregnant again.

Talk to your specialist about the best type of contraception to use while you are avoiding pregnancy.

The loss of a pregnancy can be devastating, regardless of how it happens. The long follow-up involved in molar pregnancy can also make it difficult to move forward.

You may feel very sad after a pregnancy loss. You may also feel shocked and confused, especially if this is the first time you have heard of this condition. Some people may feel anxious about the future.

Grief is individual and affects people differently. Give yourself time to grieve. Talk with supportive family and friends about your feelings.

If you have experienced a miscarriage or pregnancy loss, there are many support services available to help you, your partner and your family. Find a service that is right for you.