Pregnancy Complications

Molar Pregnancy

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A molar pregnancy is a rare complication experienced during early pregnancy. The condition actually starts during conception - when the egg and sperm meet. Sadly, the egg and sperm do not develop in the right way and the pregnancy will not be able to go to full term.

What is a molar pregnancy?

A molar pregnancy can also be known as a hydatidiform mole and is a considerably rare condition for pregnant women in the UK. Occurring in only one out of a thousand pregnancies in this country, it can be slightly more common in women of Asian origin.

In a normal pregnancy, the conception process will bring together 23 chromosomes from the mother's egg and 23 chromosomes from the father's sperm, making 46 chromosomes altogether which then develop into a healthy pregnancy. With a molar pregnancy, the amount of chromosomes combining is wrong and so the developing cells are abnormal.

Medically, there are two types of molar pregnancy, complete molar and partial molar. The complete molar pregnancy usually means that the mother's chromosomes are not present and instead the father's chromosomes are doubled. This makes it impossible for the embryo to develop and grow and instead what should become the placenta develops into a mass of cysts.

With a partial molar pregnancy the mother's 23 chromosomes are present but the father's chromosomes are still duplicated, making 69 chromosomes altogether. Again, this abnormal selection of chromosomes means that the pregnancy cannot run smoothly and although very often a placenta will start to grow and an embryo develops, the embryo will not have the right genetic set up to survive.

What causes a molar pregnancy?

Sadly, as with many pregnancy abnormalities we do not really know why these things happen. What we do know is that age can be factor as these complications are more likely to occur if the mother is over 35 years of age. You might also have problems if you have a history of molar pregnancies or are very low on Vitamin A. However, this condition is very rare and if you are having problems, talking to your doctor or midwife will help.

How do I know if I am having a molar pregnancy?

The symptoms for this condition can often be hard to spot as at first the usual pregnancy symptoms occur. As a molar pregnancy progresses, however, the symptoms may get more extreme, in particular severe nausea and vomiting will occur because hormone levels get extremely high.

Along with this you may experience a swelling abdomen that grows faster than a normal pregnancy would allow and probably becomes very tender. Bleeding is also a common symptom of a molar pregnancy and can be visible from as early as six weeks up to around 16 weeks. Bleeding is rather common during pregnancy so do not immediately assume you are having a molar pregnancy unless other symptoms are making themselves present at the same time. Sometimes a miscarriage will occur quite early on and you are unlikely to discover it was a molar pregnancy at all. Other discoveries can be made during the routine ultrasound, as a scan will show that no foetus is developing or that abnormal cysts are present in the uterus.

If a molar pregnancy is diagnosed, what will happen?

If you are experiencing problems that point to a possible molar pregnancy you will be sent for an ultrasound scan. As mentioned before, a complete molar pregnancy can be identified during a scan, but, unfortunately, a partial molar pregnancy is harder to diagnose. Usually the only way to confirm a partial molar pregnancy is to perform tests after a miscarriage has occurred, which can be quite a distressing thought.

Because the pregnancy will not progress you are likely to be offered a minor operation called a dilation and curettage, which essentially removes the abnormal tissues from your uterus. You may also be prescribed medicines to let your body shed any left over tissues after the operation. Your doctor will monitor you closely over the next six months, requesting regular blood samples to check that your hCG hormone levels start to decrease properly - a sign that your body is returning to normal and you are getting better.

What if I don't start to feel better?

In a very small amount of cases some molar tissue gets left over and may start to grow into the wall of the uterus, or more dangerously, be transferred to other organs via the bloodstream. This condition is known as persistent gestational trophoblastic disease and can easily be treated. The signs that you may have this disease is continued bleeding after your operation and when blood tests that show your hCG levels are not returning to normal.

If this happens you will be offered chemotherapy at a specialist centre to kill off any remaining cells. Thankfully, with prompt diagnosis and treatment cases are totally curable.

How will this affect me?

As with any type of loss, a molar pregnancy can be a frightening and emotional time, especially as this condition is quite rare and not much is known about it. Thankfully, there are specialist centres within the UK and online that can offer emotional support and much needed information on the condition. Taking time to recover, staying healthy and sharing your emotions with others can help you feel more like your normal self.

Can I prevent this from happening to me?

Unfortunately, as with many rare pregnancy conditions, little is known about why these abnormalities occur. As with any pregnancy, make sure you are staying healthy and valuing good nutrition during conception as well as pregnancy. The good news is that further pregnancies will not necessarily encounter the same problems and most couples go on to have healthy pregnancies and healthy babies.

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This internet site provides information of a general nature and is designed for educational purposes only. If you have any concerns about your own health or the health of your child, you should always consult a doctor or other healthcare professional.