You have been diagnosed as having a molar pregnancy, although highly treatable this is still extremely serious and requires careful follow-up.

This leaflet will explain what a molar pregnancy is and why it is important for you to have follow-ups by the specialist screening centre located in London.

A molar pregnancy or as it is known medically, a Hydatidiform mole, is a pregnancy in which the placenta 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 1 in 1,200 pregnancies.

Sadly a molar pregnancy is a sure form of early pregnancy loss.  This means there is no possibility that your pregnancy can survive.

There are two types of molar pregnancy: a complete and a partial hydatidiform mole.

Complete Mole

This condition results when the sperm fuses with an egg that does not carry any genetic material.  These complete moles are derived entirely from the cells of the father.  When this fertilised egg grows, no embryo is present in the pregnancy sac, only the placenta.

Partial Mole

These are much more common and usually mimic the appearance of an incomplete miscarriage.  In this condition the egg allows two sperms to fertilise it.  The embryo has three sets of chromosomes instead of the usual two so the baby would be abnormal and could never survive.  Very rarely a partial mole develops into an invasive mole, but seldom develops into a cancer.

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 hydatidiform mole can develop into a choriocarcinoma, which is a form of cancer – however, the cure rate is almost 100 per cent.  This is why molar pregnancies need careful follow up.


A molar pregnancy will probably cause bleeding and the womb will seem bigger than it should be.  Sometimes it can cause high blood pressure and thyroid problems.  There may be increased nausea.

The overgrown placenta tends to produce excessive amounts of the pregnancy hormone hCG (human Chorionic Gonadotrophin).  Most of the symptoms of a molar pregnancy are caused by the high hormone levels.

Diagnosis is made by:

  • Detecting very high levels of hCG in the blood
  • An ultrasound scan showing the particular appearance of a molar pregnancy
  • Examination of the tissue by the pathologist


Surgical evacuation

You will be admitted to hospital to have a ERPC – a surgical removal of pregnacy tissue.

If your admission is planned for the Day Surgery Unit you will be discharged the same day.  However, an overnight stay is sometimes necessary.

Blood levels of the pregnancy hormone hCG are measured weekly following a molar pregnancy.  You will be registered at the specialist follow-up centre at Charing Cross Hospital, London by your gynaecologist.

You will receive a letter from the follow up centre confirming that you have been registered for follow up care.  There are other regional centres for registration of a molar pregnancy in Sheffield and Dundee.

You do not have to travel to London.  The necessary kit will be sent to you by the screening centre.  There will be a letter for your GP and tubes for urine and blood samples in the kit.  Follow the instructions given.  The results of the follow-up will be sent to your GP and your gynaecologist.

The normal level of the pregnancy hormone hCG in the blood is less than 5 IU/l.  Once the blood tests are normal, only urine samples will be needed.  Remember that urine samples should always be the first urine of the day.

The minimum period for follow-up of complete and partial moles is six months. If you need treatment then, you are followed up until your hCG values remain normal.


You may well feel upset after losing the pregnancy.  Also you may be worried about the molar pregnancy settling down. As time passes, more often than not you learn to cope with your loss but if you need advice or support please do not hesitate to call us.

Do not get pregnant whilst you are being followed up.  It will become difficult to know if your hCG levels are rising due to pregnancy or re-growth of the mole.

You will need to wait until six months and after the hCG levels have returned to normal.

It is very important that you tell the follow-up centre if you do become pregnant.

What are the risks of having another Hydatidiform Mole?

The chances of having a perfectly normal pregnancy are very good.  The risk of further molar pregnancy is low (1:55).

It is important that you discuss contraception with your GP/consultant.  It is not advisable to use the contraceptive pill because if your hCG levels are above normal, taking the pill may prolong the life of any remaining molar
tissue.  However, the contraceptive pill can be used safely after the hCG levels have returned to normal.

The coil is also best avoided until hCG levels are normal.

Condoms or caps may be used.


Early Pregnancy Assessment Clinic (EPAC)
Tel: 01935 384385

Miscarriage Association
Tel: 01924 200799

Counselling 4 Yeovil
Tel: 07896630296


Review: 06/23
Ref: 14-17-180