Pre-birth testing

Pre-birth testing is part of a broad set of issues to do with human reproduction. Reproductive technologies are being used more and more; with increased use come certain moral, ethical and social questions. These might have profound implications for the way we think about reproduction and the family.

Toi te Taiao: the Bioethics Council has produced this document with the intention of stimulating deliberation and discussion on these important issues. The approaches in this document reflect the interests, concerns and values that the Council heard from 56 members of the public at preliminary workshops.

You are participating in one of 18 deliberative dialogue events that are being held throughout the country. The results of these events will be reflected in a report to Government; it is expected that policy and decision makers will take the recommendations seriously when they address issues about pre-birth testing.

Development of pre-birth testing

If you ask people who are about to have a baby what they want for their child they will often say ‘a healthy baby’. Others might want to know the sex of the baby. These wishes are not new.

By the 1890s public health advocates started to encourage women to see their doctors as soon as possible after pregnancy was suspected. Prenatal care was found to improve the health of both infants and mothers, even though most women did not see a doctor or midwife until well into the pregnancy.

In 1959 it was discovered that people with Down syndrome[Called Down’s syndrome in British English.] have an extra chromosome 21. This was the first time that a disability and a chromosome disorder had been linked.

By 1968 it was possible to test some cells from the fluid surrounding the foetus to detect some genetic disorders, although this process (called amniocentesis) has some risks for the pregnancy. From the 1970s, amniocentesis was frequently offered to older women because it was known that Down syndrome is more common if the mother is older.

By the 1980s, ultrasound tests became available and it was possible to see whether the foetus appeared to be developing well or whether there were certain foetal abnormalities. It was also possible to measure the fluid-filled area at the back of the foetus’s neck: an increase between 11 and 14 weeks into the pregnancy is associated with Down syndrome. It can be detected by a nuchal translucency measurement (NT screening).

NT screening is more reliable if combined with testing blood from the pregnant woman, as well as taking into account the age of the mother. If the screening indicates a possible problem, the woman is offered an invasive diagnostic test using cells taken by amniocentesis or chorionic villus sampling (CVS). These tests can identify a number of other conditions in addition to Down syndrome.

Preimplantation Genetic Diagnosis (PGD)

Before the 1970s, if people knew there was a genetic condition in their families which they did not want to pass on to their children, they had two choices: either not to have children or the woman would become pregnant then test for the condition. If the result was positive the woman or couple would choose whether or not to continue the pregnancy.

In 1978, Louise Brown was born, the first baby from an embryo created outside the mother using in vitro fertilisation (IVF). From then on, many more choices became possible. In the mid-1980s, research began in the United Kingdom to find out whether an embryo created through IVF could be tested using preimplantation genetic diagnosis (PGD) to diagnose genetic conditions. PGD involves removing one or two cells from a number of embryos and testing the cells for a genetic condition. Embryos free of the condition are chosen to be transferred to the mother.

As we understand more about genetics, more testing will become possible. Some tests will relate to medical conditions, while others might relate to other characteristics, such as height or eye colour.

‘Saviour siblings’

Sometimes a sick child with a serious medical condition, such as certain blood conditions[An example is Diamond Blackfan Anaemia (DBA), a blood condition caused by a failure within the bone marrow.] can only be treated by using tissue which is matched to that child. If there is no matching donor available, parents might choose to use PGD for tissue typing to ensure that the new baby will be a genetic match to the sick child. The new child is sometimes called a ‘saviour sibling’. Generally, the umbilical cord blood from the baby is used to treat the sick child.

Using PGD to have a ‘saviour sibling’ must be approved by an ethics committee on a case-by-case basis. The current guidelines state that:

• the sick child must suffer from a single-gene disorder or familial sex-linked disorder [A genetic disease is sex-linked, if a mutant gene is part of the X chromosome (females have two X chromosomes per pair of such sex chromosomes, males have an X chromosome and a Y chromosome). All male offspring are affected because the Y chromosome of the XY pair does not have a compensating normal gene. Because the mutation is on the X chromosome, however, and males transmit only the Y chromosome to their sons during fertilisation, males do not transmit the disease to male offspring but only to female offspring.]
• the parents must only intend to use the cord blood of the saviour sibling
• there must be no other treatment available
• the embryo must be a sibling of the affected child.

At present in New Zealand, PGD for tissue typing is only allowed if the sick child has a condition that the new baby might also inherit. Therefore there must be two purposes: to ensure that the new baby’s cord blood will be suitable to treat the sick child; and to prevent the baby from inheriting the condition. It cannot be used to produce a ‘saviour sibling’ for a child with a condition that is not inherited, such as leukaemia. The New Zealand guidelines for the use of PGD are currently being reviewed by the Advisory Committee on Assisted Reproductive Technology (ACART).

What are the legal limits?

In New Zealand, the legal position relating to pre-birth testing is:

• testing may be carried out during pregnancy
• abortion is legal up to 20 weeks gestation if there is a serious danger to the mental or physical health of the mother or a substantial risk that the child would be seriously handicapped
• abortion is only permitted beyond 20 weeks gestation if it is necessary to save the life of the woman or prevent serious permanent injury to her physical or mental health
• PGD may not be used[Human Assisted Reproductive Technology Act 2004, s11.]:
• for non-medical sex selection (such as parents who want to balance their families, by having boy/s and girl/s)
• to alter the genetic constitution of an embryo
• to select embryos with a genetic impairment seen in a parent
• PGD may be used in the following situations without ethics committee oversight:
• a single-gene disorder has been identified in the family and there is a 25% or greater risk of an affected pregnancy
• for sex determination if familial sex-linked disorders have been identified in the family and no test is available for the specific mutation
• for familial chromosomal disorders if the disorder has been identified in the family
• for non-familial chromosomal disorders if the woman is of advanced reproductive age, or has had recurrent implantation failure or miscarriage.

As well, the disorder must be going to cause the child to be ‘seriously impaired’. The fertility clinic and a clinical geneticist must decide whether the disorder is likely to be serious.

• Any other uses of PGD must have ethics committee approval.

Let’s deliberate!

Many families have been able to avoid having children who would suffer from painful, disabling or fatal conditions by using pre-birth testing. Some people have concerns about testing and there is significant disagreement about the best response to these concerns. This choicebook presents four perspectives (called approaches), about how we, as a society, should deal with pre-birth testing.

Each perspective presents arguments supporting that approach and recommendations for specific actions. Each approach has advantages and disadvantages which are outlined in the ‘in support / in opposition’ boxes at the end of each section.

You do not have to select just one approach. In fact it is very likely that during discussions with other participants, you will find that there are aspects of other approaches that appeal to you. Using insights from a range of approaches is what deliberation is all about.

This choicebook is intended to encourage rewarding discussions between people about the issue of pre-birth testing. When we know what others believe about the issue, we can have reasoned respectful dialogue about how to best respond to the challenges and opportunities posed by pre-birth testing.

Approach one: ‘My choice my right’

Deciding whether or not to have pre-birth testing and then deciding what to do in response to the results is regarded as a matter for the mother / parents. Nobody else should be able to interfere with these decisions. This approach promotes personal responsibility and the freedom to make our own choices.

Approach two: ‘Life is a gift’

People who support this position would not allow any decision to destroy an embryo or terminate a pregnancy, because every embryo or foetus has a right to life. This approach suggests that when it comes to unborn children, we should interfere with nature as little as possible.

Approach three: ‘Tangata whenua’

This approach holds that it is important that Māori values and the Treaty of Waitangi are taken into account appropriately. Efforts are needed to inform and empower Māori, to enable them to develop tikanga[For an approximation of the meaning of Māori terms, see the glossary.] about pre-birth testing and have these tikanga respected by health providers and scientists.

Approach four: ‘It's about information, knowledge and the pubilc's involvement’

This means that better information about pre-birth testing needs to be widely available and in more accessible forms. The development of these resources needs to include people’s perspectives, interests and knowledge as well as medical facts.

Let’s now look at these approaches in more detail.

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