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Chromosomal Abnormalities and Abortion

People consider abortion for all kinds of reasons, including when an issue has been detected during antenatal testing. If your ultrasound scan or other tests have revealed that your baby is affected by a chromosomal abnormality, then you may be considering your options, including termination of pregnancy.

What is a Chromosomal Abnormality?

Our DNA is organised into 23 pairs of chromosomes. We usually inherit one of each pair from our fathers and the other from our mothers. However, sometimes an accident happens when cells are dividing. An extra copy of one of the chromosomes can be included in an egg or sperm cell, or one of the copies may be missing completely. When these cells go on to make a baby, it will have the wrong number of chromosomes. This is known as a chromosomal abnormality.

In most cases, chromosomal abnormalities are fatal and the pregnancy will end naturally, often before the mother realised she was pregnant. However, in some cases the pregnancy can survive longer and in some cases babies can be born with chromosomal abnormalities.

The most common chromosomal abnormalities to be detected during pregnancy are:

  • Down’s syndrome (usually due to an extra copy of chromosome 21)
  • Edward’s syndrome (extra copy of chromosome 18)
  • Patau’s syndrome (extra copy of chromosome 13)
  • Sex chromosome conditions

The effects of these conditions can be very serious, especially in the case of Edward’s and Patau’s syndromes, which will usually be fatal during the pregnancy or soon after birth. Many women will therefore consider termination of pregnancy if their baby is diagnosed with one of these conditions.

How Are Chromosomal Abnormalities Detected in Pregnancy?

Chromosomal abnormalities are most often detected during the nuchal scan or 12 week ultrasound. However, this is a screening test that can only tell you if your baby is at higher risk of Down’s, Edward’s or Patau’s syndromes. You will need to have an amniocentesis or chorionic villus sampling (CVS) to confirm the diagnosis. You might also have a special blood test called Non-Invasive Prenatal Testing (NIPT) to detect chromosomal abnormalities, including sex chromosome conditions.

Considering Your Options

If a chromosomal abnormality is detected during your antenatal screening, then you will need to discuss the results in detail with your doctor. It’s important for you to know how reliable the test results are and what the diagnosis means for you and your baby before considering options such as termination of pregnancy.

The effects will depend on the specific condition that is affecting your baby. Patau’s and Edward’s syndromes usually cause very severe intellectual and physical disabilities. Most babies diagnosed with these conditions won’t be able to survive longer than a year. However, babies born with Down’s syndrome can live long and fulfilling lives, despite having some learning difficulties and physical effects. However, the effects can vary and raising a child with a condition like Down’s syndrome isn’t always easy or possible in every situation.

Understanding the diagnosis and learning more about how it could affect you, the child, and the rest of your family can help you to make the right decision about termination of pregnancy. You should discuss all of the options with your doctors but remember that it is your decision in the end. What is right for one person isn’t always right for another. Some women want to continue their pregnancy for as long as possible, while others decide that termination of pregnancy is the best choice for their health and emotional wellbeing.

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