Virtus Genetics
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Miscarriage causes & recurrent miscarriage

Sadly, we know that miscarriage occurs in approximately  one in four pregnancies. This is however little consolation when you have lost a baby through miscarriage. You may want to find out why it happened  and if you can reduce the risk of it happening again.

The vast majority of patients who have experienced a miscarriage will go on to achieve a healthy family, so it’s important to stay positive. However, a small percentage of couples will experience more than one consecutive miscarriage. If you have three or more consecutive early pregnancy losses this is called recurrent miscarriage, and affects about 2% of women trying to have a baby.

What causes a miscarriage?

Some of the causes of miscarriage include:

  • Chromosome variations
  • Genetic variations
  • Uterine variations
  • Immune causes
  • Blood clotting disorders
  • Hormone imbalances
  • Other medical conditions

Chromosomal variations - genetic problems with the embryo

Chromosomal variations in the embryo are a common cause of early miscarriage

Up to 70% of embryos, whether created naturally or through IVF, are lost before birth. This usually occurs within the first three months of pregnancy, most often before implantation.

What is a chromosome?

Chromosomes are long strands of DNA found in the cells of the body. DNA contains genes that provide the code for our bodies to grow, develop and function normally. A normal cell  contains 23 pairs of chromosomes. Fertilisation combines 22 chromosomes and an X chromosome from the mother’s egg with 22 chromosomes and either an X or Y chromosome from the father’s sperm. An embryo  has 46 chromosomes – if it’s a female, it has two X chromosomes, and if it’s a male, it has an X and a Y chromosome.

If the cells of an embryo contain the wrong number, of chromosomes either too many or not enough this is called aneuploidy, and causes the embryo to develop abnormally. Women over 38 years of age are at greatest risk of conceiving a baby with a chromosomal variation.

Sometimes pieces of chromosomes break off and attach to the ends of other chromosomes. This is called a chromosome translocation. The translocation is called balanced if there is no gain or loss of chromosomal material and does not cause any health problems. A carrier of a balance translocation can may have eggs or sperm with the incorrect amount of chromosomal material. This is because when eggs and sperm are formed, a parent only passes on one of each of their chromosomes from each chromosome pair. This could result in an embryo with unbalanced chromosomal translocation and this can result in early miscarriage or structural abnormalities in a baby, depending on the chromosomes involved.

Testing for genetic conditions

A gene is a sequence of DNA (or genetic code) on a chromosome with a particular function. Humans have approximately 20,000 different genes. When the DNA sequence of a particular gene is altered, a genetic variation can result in a health condition.  It is now possible to test embryos for many single gene disorders or chromosomal variations with Pre-implantation Genetic Testing (PGT).

Some of the most common conditions tested for include:

  • Huntington's disease (direct and exclusion)
  • Cystic Fibrosis
  • Thalassaemia
  • Duchenne muscular dystrophy
  • Fragile–X syndrome
  • BRCA1/BRCA2 (hereditary breast / ovarian cancer)

Advanced embryo selection

The  Virtus Health Group has been involved in a scientific breakthrough with the world’s fastest and most precise embryo selection testing.

By screening all chromosomes in a developing embryo an embryo with the greatest chance of a successful pregnancy  can be selected . This can address some of the key causes of miscarriage, and give some certainty to couples who have experienced recurrent miscarriage.