A molar pregnancy occurs when the fertilisation of the egg by the sperm goes wrong and leads to the growth of abnormal cells or clusters of water filled sacs inside the womb. It is a type of gestational trophoblastic disease.
Vaginal bleeding is the most common symptom of a molar pregnancy. Bleeding can happen during a normal pregnancy too and is not always serious, but you should tell your doctor or midwife straight away if you have any bleeding.
Women with a molar pregnancy are more likely to pass blood clots or have a watery brown vaginal discharge. Some women pass pieces of the molar tissue, which can look a bit like small bunches of grapes. Bleeding caused by a molar pregnancy usually begins between weeks 6 and 12 of pregnancy.
Less common symptoms
The following symptoms are uncommon. This is because most molar pregnancies are found during routine ultrasound scans carried out in early pregnancy.
In some women who have a complete molar pregnancy the abdomen might get bigger more quickly than in a normal pregnancy. So your doctors or your midwife may say that you are large for your dates. In women with a partial molar pregnancy, the womb and abdomen might be smaller than expected for the stage of pregnancy.
Feeling and being sick
Feeling and being sick are common in a normal pregnancy. But with a molar pregnancy the sickness can be more severe and might happen more often. This is called hyperemesis.
Anaemia (low red blood cells)
Anaemia means that you have a low number of red blood cells in your body. Red blood cells carry oxygen around your body. If you're losing blood because of vaginal bleeding, your red blood cell count may get low. Being anaemic can make you feel tired and breathless.
Pre eclampsia is a complication that can occasionally happen in the last 3 months of a normal pregnancy. The main symptoms are high blood pressure and protein showing in your urine. Rarely, with a molar pregnancy you can get pre eclampsia much earlier on.
This is a rare symptom of molar pregnancy. The medical term for this is hyperthyroidism.