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01st May 2024

What is a molar pregnancy? The causes, symptoms, diagnosis and treatment

Sophie Collins

Molar pregnancy

A molar pregnancy occurs in about one in every 600 pregnancies

According to figures, this means there would be around 120 cases each year in Ireland.

The lesser-known pregnancy complication is a rare, complex condition that can affect women during their reproductive years. 

Understanding its causes, symptoms, and treatment options is crucial for expectant parents.

Here’s what you need to know:

What is a Molar Pregnancy?

According to the HSE, this condition is also known as gestational trophoblastic disease (GTD), is an abnormality of the placenta where a non-viable fertilised egg implants in the uterus. 

This abnormal tissue growth can lead to complications if left untreated.

Causes of Molar Pregnancy

The exact root cause of molar pregnancy is not fully understood, but the Cleveland Clinic explains that it occurs when an egg and sperm join incorrectly at fertilisation and create a non-cancerous tumour.

There are certain risk factors that may increase its likelihood, including:

  • Maternal Age: Women under 20 or over 35 have a higher risk
  • Previous Molar Pregnancy: Having had a molar pregnancy increases the risk of recurrence.
  • Diet: A diet low in carotene-rich fruits and vegetables may be a contributing factor.

Types of Molar Pregnancy

There are two main types:

  • Complete: This occurs when there is an empty egg (no fetal development) and abnormal placental tissue.
  • Partial: This involves both abnormal placental tissue and a fetus with severe abnormalities.

Symptoms of Molar Pregnancy

Symptoms can mimic those of a normal pregnancy but may include:

  • Vaginal bleeding
  • Severe nausea and vomiting
  • Enlarged uterus
  • High blood pressure
  • Hyperthyroidism


A molar pregnancy is typically diagnosed through:

  • Ultrasound: To visualise the abnormal growth in the uterus.
  • Blood Tests: Elevated levels of human chorionic gonadotropin (hCG) may indicate molar pregnancy.


Treatment usually involves:

  • Surgical Removal: Dilation and curettage (D&C) to remove the abnormal tissue from the uterus.
  • Monitoring: Regular follow-up appointments to ensure hCG levels return to normal.
  • Contraception: Avoiding pregnancy for at least six months after treatment.

Emotional Support

Dealing with a molar pregnancy can be emotionally challenging. Seeking support from loved ones, support groups, or mental health professionals can help you to deal with feelings of grief and uncertainty.

Future Pregnancy

Most women who have had this condition go on to have healthy pregnancies in the future. 

However, they do need to closely monitoring by a healthcare provider is essential to detect any recurrence or complications early on.

While it can be distressing for expectant parents, early diagnosis and appropriate treatment can lead to positive outcomes. 

By understanding the causes, symptoms, and treatment options, people can navigate this challenging experience with knowledge and support. 

If you suspect a molar pregnancy or have concerns about your pregnancy, it’s important to consult with a healthcare provider promptly.