Molar pregnancy – what you need to know

22 May Molar pregnancy – what you need to know

When you’re trying for a baby, it’s devastating when things go wrong. One rare complication that can cause particular heartbreak is molar pregnancy. Strange name, so what exactly is it?

A molar pregnancy, sometimes called hydatidiform mole, occurs when the placenta and foetus don’t form properly. It’s a fertilisation problem: the genetic information in the egg and sperm don’t speak to each other. So instead of a viable pregnancy, you end up with an abnormal set of water-filled cysts.

There are two types of molar pregnancy. The first is called a partial molar pregnancy, where a normal egg is fertilised by two sperm (i.e. two sets of male chromosomes). The second is a complete molar pregnancy, when an egg with no genetic material fuses with a sperm. Either way, normal fetal development fails.

Around 1 in 1,000 pregnancies result in a molar pregnancy. It’s incredibly unfortunate and upsetting when it occurs. But ‘moles’ don’t happen because of something you did or didn’t do. It’s just very bad luck.

How is a molar pregnancy diagnosed?

One of the many stressful aspects of a molar pregnancy is that you may think you’re pregnant. Your HCG levels are sky-high. You’ll have the usual pregnancy symptoms. All seems fine. Only an ultrasound scan will reveal the truth. It’s yet another reason why all pregnant women should have an early scan at six or seven weeks.

That said, only a complete molar pregnancy can usually be seen early on. A partial molar pregnancy can resemble a normal foetus. This false sense of reassurance makes a later diagnosis all the more painful.

Some women have symptoms. These may include vaginal bleeding, a swollen abdomen, high blood pressure, severe nausea and vomiting. Others feel nothing. Quite often, a molar pregnancy is only confirmed after a miscarriage.

What happens if I have a molar pregnancy?

If you’re diagnosed with a molar pregnancy, action is needed. It has to be removed. There’s no chance a baby can develop and it’s harmful for you to keep the tissue in your womb.

Surgery may be the last thing on your mind. But the usual approach is to have either a D&C (dilation and curettage) or an ERPC (excavation of retained products of conception). The exact treatment you’ll have depends on whether you have a partial or complete molar pregnancy. The aim is to remove all the tissue and cells.

You’ll then be referred to a specialist. It can take a while for your HCG levels to come down; you’ll be monitored until they do. For 1 in 10 women, HCG levels don’t decrease. This means there are still some cells left in your body and you may have persistent trophoblastic disease. Don’t panic.

As the cells can grow into a new gestational trophoblastic tumour – and sometimes grow quickly – further treatment will be required. The usual approach is to have a low dose of chemotherapy. This sounds scary, but you have an 80% chance of the growth being benign. The ‘cancer’ element naturally causes even more distress.

What about future pregnancies?

If you’ve suffered the trauma of a molar pregnancy, it doesn’t mean you’ll have another one. The risk of a second molar pregnancy is tiny – about 1 to 2 per cent. You’ll have to wait at least six months before trying again. If you’ve had chemotherapy, the suggested recommendation is a year.

A molar pregnancy is more likely in women over 40 or in teenage pregnancies. If you’re Asian, you’re twice as likely to have one. For IVF patients, a PGD-tested embryo can virtually eliminate the risk of a molar pregnancy. PGD is a great option if you have a family history of molar pregnancy or had one before.

It’s devastating and alarming to experience a molar pregnancy. Some women say it’s harder to deal with than a miscarriage because of the protracted medical intervention needed. Just remember two things. One: your chances of having one are low. Two: treatment is effective. You can go on to have a perfectly healthy pregnancy and put the problem behind you.