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Molar pregnancy

About this leaflet

You have been diagnosed as having a Hydatidiform Mole, also called a molar pregnancy. Sadly, a molar pregnancy is a type of early pregnancy loss. This means there is no possibility that your pregnancy can survive. The loss of your baby is likely to make you feel very sad. In addition, this may be the first time you have heard of this condition and so you may also feel shocked, confused and anxious about the future.The purpose of this leaflet is to explain fully what a molar pregnancy is, and why it is necessary for women who have had a molar pregnancy to be followed up by a specialist gynaecologist obstetrician. It is important that you understand exactly what has happened to you, and what treatment is required.

How a normal pregnancy develops

At the time of fertilisation, the genes from the sperm mix with those from the egg to produce the individual features of the baby to be. By the time the fertilised ovum has reached the womb, all the information has been exchanged and it has divided into two main groups of cells. The trophoblast is that part from which the placenta (afterbirth) and membranes develop. It grows into the lining of the womb to anchor the pregnancy and allow it to grow. The placenta forms and so does the embryo and after a few weeks it becomes a recognisable baby. The baby grows and his or her organs gradually become able to function on their own and, after about 40 weeks since the last period, he or she is born. Many pregnancies, possibly 50 to 60 percent, are lost before they can implant, or within the first three months. This is called a miscarriage. Rarely, other problems can arise and molar pregnancy is one of these.

What is a molar pregnancy?

A molar pregnancy is a pregnancy in which the trophoblast develops into a mass of fluid-filled sacs that resemble clusters of grapes. It grows in an uncontrolled fashion to fill the womb. It occurs in about one in 1200 pregnancies. There are two types of molar pregnancy: a complete and a partial molar pregnancy. Occasionally the molar tissue persists and may start to grow and spread; this is a very rare complication of molar pregnancies.

What is a complete molar pregnancy?

In a normal pregnancy, an egg and sperm fuse together and share genetic material. Sometimes the egg does not carry any genetic material so that when the sperm fuses with it, no sharing can take place. Usually the fertilised egg dies at that point but, rarely, it goes on to implant in the womb. When it does, no baby grows, only the trophoblast, and it grows in a disorganised way. This produces the complete molar pregnancy.

What is a partial molar pregnancy?

A partial molar pregnancy is much more common than a complete molar pregnancy. In this situation two sperms fertilise the egg (this should be impossible). There is too much genetic material and, as a result, the pregnancy develops abnormally, with the placenta outgrowing the baby. A baby may or may not be present and even if it is present, it does not develop normally.

If this is such an abnormal pregnancy, why do I feel so pregnant?

The overgrown placenta tends to produce massive amounts of the pregnancy hormone hCG (human Chorionic Gonadotrophin). Most of the symptoms of a molar pregnancy are caused by these high hormone levels. A molar pregnancy will probably bleed and the womb will seem bigger than it should be. Sometimes it can  cause high blood pressure and thyroid problems. There may be increased symptoms of morning sickness.

How is a molar pregnancy treated?

You will be admitted to hospital to have a small operation to empty your uterus. This procedure is carried out under a general anaesthetic in the operating theatre. Instruments are used to ensure the inside of your uterus is empty. The operation usually takes about 5 to 10 minutes, and is done vaginally so you will have no cut/stitches. The tissue will be sent to the laboratory for examination and you will be told the result. It is important that you understand that this is not a ‘termination of pregnancy’ or ‘abortion’. In most cases there never was a baby or the baby would never develop with such abnormal chromosomes. While you may feel sad at the loss of your pregnancy, please try not to feel guilty as there is nothing you could have done to prevent this happening.

Are there any risks with this operation?

Like all operations, small anaesthetic and surgical risks are involved. There is a small risk of infection or injury to the womb or cervix. Injury to the womb occurs about once every 200-500 operations. The injury is usually small and of little consequence. Very rarely this injury may be more significant requiring further surgery at the time to repair the damage.


What to expect after the operation


In the 24-hour period after the anaesthetic you will probably feel tired and you should not drink alcohol, drive, or operate any dangerous machinery.


The bleeding is usually less than a period, and should have stopped in about seven days. If you are still bleeding on the tenth day, or if your loss increases and becomes heavier than your normal period, or starts to smell offensive, you should contact the EPAU or your GP.


After the operation you may have a dull ache in your lower stomach—this is normal for a few days.


While your bleeding continues, it is best to use sanitary pads instead of tampons, as this will reduce the risk of infection. Baths or showers can be taken as required.


Your breasts may be tender for several days and you may even leak milk. In this case wear a well fitting bra, day and night, to provide adequate support until your breasts are comfortable. This may be necessary for a couple of weeks, but will usually settle on its own. If painful, mild painkillers such as paracetamol can be used. Testing to see if there is milk causes a reflex stimulation of milk production, and should therefore be avoided.

Why are molar pregnancies followed up?

Occasionally the molar tissue may persist and grow deeper into the wall of the uterus and spread; this is an invasive mole. Very rarely a molar pregnancy can develop into a choriocarcinoma which is a form of cancer. Thankfully the cure rate is almost 100%. This is the reason why molar pregnancies are followed up.

What follow up is required?

Blood levels of the pregnancy hormone hCG are measured weekly following a molar pregnancy until the pregnancy hormone level is so low that it can no longer be detected. In most women the levels of hCG drop fairly rapidly. Once your hormone level reaches zero for three weeks you will progress to monthly blood tests for a period of time (usually six months). The period of time required for follow-up tests is variable and dependant on a number of factors. The EPAU coordinator will let you know how long you will need to be followed up. We will phone you after every test to let you know the results and copies of these results will be sent to your GP.

It is extremely important that your have all follow up tests as ordered. If you have any problems with this please contact EPAU on 07 3163 5132.

What happens if I have a choriocarcinoma or an invasive mole?

You will be given clear advice and guidance in the very unlikely event that you develop either of these conditions. Investigations, e.g. ultrasound, X-ray, CT or MRI scans, may be needed to check the extent of any problem. Treatment is very successful using drugs (chemotherapy) and once treatment has been completed successfully, further pregnancies are possible. There is no increased risk of abnormal babies in women who have had chemotherapy.

Do I have cancer?

If you have a molar pregnancy or invasive mole, then you do not have cancer. However a small proportion of molar pregnancies can develop into a choriocarcinoma, which is a form of cancer. Fortunately it is a cancer with an excellent cure rate.

Am I going to die?

Most emphatically, NO. Women do not die these days from molar pregnancy or invasive mole and only very, very rarely from choriocarcinoma.

Can I get pregnant again?

Yes. A molar pregnancy does not affect your fertility at all. Many women have gone on to have babies following a molar pregnancy

When can I fall pregnant again?

We would advise that you do not fall pregnant while you are being followed up. It will become difficult to know if your pregnancy hormone levels are rising due to pregnancy or re-growth of the molar tissue. We advise you to wait until after your follow-up period before trying for another pregnancy. It is very important to tell us if you become pregnant.

What about contraception?

Contraception needs to be discussed with a primary healthcare provider, such as a GP, to ensure advice provided is based on the individual circumstances and needs of each woman.

What are the chances of another molar pregnancy?

It is possible, but very unlikely. The risk of a further molar pregnancy is one to two per cent only. However, the chances of having a perfectly normal pregnancy are excellent. In future pregnancies, an early ultrasound scan, at approximately eight weeks, may help to reassure you and your doctor.

Am I more likely to have a miscarriage?

We do not know for certain, but the answer is probably no.

Can I do anything to reduce the risk of another molar pregnancy?


Can my partner catch anything from me because I have had a molar pregnancy?



We understand that the experience of a molar pregnancy can be very distressing. Not only have you lost your baby, but also you need to have continued medical follow-up to check your hCG levels. This may mean a lengthy period of anxiety. You may also feel like you are “in limbo”, unable to move on after this pregnancy and having to delay trying again. You may find that family and friends don’t understand what you are going through and this can make you feel quite isolated. If you would like to talk to someone else who has been through a molar pregnancy and who can offer support, please contact us. We will always try to help.

Early Pregnancy Assessment Unit
Level 7, Mater Mothers’ Hospitals
Raymond Terrace
South Brisbane Qld 4101
Telephone: 07 3163 5132

© 2013 Mater Misericordiae Ltd. ACN 096 708 922

Mater acknowledges consumer consultation in the development of this patient information.
Mater Doc Num: HOSP-011-00978, HOSP-005-00805
Last modified 03/11/2015.
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