CAREunity is a test which identifies one of the causes of recurrent miscarriage and other placental problems

In the last 10 years there is no other area of medicine that has progressed more rapidly than the assisted reproduction field. One of the most exciting new developments is a test called CAREunity, which is also known as C4M2 Variant or Annexin A5 M2 Haplotype.

We always work hard to do everything possible to help our patients. Miscarriage is particularly distressing and our teams at CARE have been working on a test which we believe can identify one of the causes of miscarriage. 

CAREunity is designed to help people who have experienced repeated unexplained miscarriages or unexplained implantation failure with IVF treatment. It looks at a genetic "mutation" or "variation" in a specific gene carried on chromosome no. 4. That is where it gets the name C4M2. "C4" stands for chromosome no. 4 and "M2" is the name given to the variant at a specific location of this gene on chromosome 4.

The cells of our body usually have 23 pairs of chromosomes, including one of each pair from the egg and one from the sperm. Each chromosome carries the genes responsible for every function in our body, this is what keeps us alive and healthy.

The Annexin A5 gene

The Annexin A5 gene is partly responsible for normal clotting in our body and the presence of the variant gene can be associated with blood clotting disorders (sticky blood). We have known for a number of years that increased clotting in the placenta can lead to miscarriage or implantation failure by reducing the blood flow to the embryo at a very early stage of its implantation in the womb. It has also been shown that the presence of this gene in the embryo can cause other conditions from a poorly functioning placenta (due to micro-clots in the blood flow system between fetus and placenta) which can be associated with high blood pressure and small-for-dates babies. What is new following the discovery of the Annexin A5 variant (C4M2) is that it is the presence of the variant gene in the embryo that can cause clotting problems - this is important because the embryo can inherit the variant gene from either the sperm provider or the egg provider. 

How does the CAREunity test work?

This screening test can identify the presence of the Annexin A5 gene. If the gene is present in either the sperm of the egg provider then there is at least a 50% chance it will be present in the embryo.

Testing for it is simple, a swab is taken from the inside of the mouth of both partners and the results are available in about 3 weeks. If the Annexin A5 Variant is identified in either partner the woman having embryo transfer will be prescribed a blood thinning medication called Heparin, better known as Clexane. This is an under the skin injection that starts at the time of embryo transfer and continues until at least 12 weeks of pregnancy. 

The CAREunity test is available at all CARE clinics - contact us to find out more.


When you’re ready to talk about your next step, we’re here and all of our teams will be dedicated to providing you with the highest standards of care.

HFEA Comment

The independent regulator of fertility treatment, the Human Fertilisation and Embryology Authority (HFEA) consider that the only way to be confident that a treatment is effective enough to be used routinely is to carry out a randomised controlled trial (RCT). In an RCT, patients are assigned randomly to two groups: a treatment group, given the new treatment and a control group, given either a well-tried treatment or a placebo.

The CAREunity test has not been subject to a Random Controlled Trial (RCT) and supporting evidence is limited. It is therefore important that you discuss with your consultant whether it is suitable for you before making a decision on whether to include the test in your treatment.