Researchers are urging for a reevaluation of the 14-day limit on studying embryos, arguing that extending this restriction may lead to a better understanding of recurrent miscarriages and congenital conditions.
Previously, researchers have only been able to grow embryos up to the equivalent of 14 days of development in their studies of early life. After that point, they rely on pregnancy scans and donated material from terminations to continue tracking the development process.
However, this results in a gap of approximately two to four weeks during development that has not been extensively researched. Scientists believe that this period, known as the “black box,” could be crucial in enhancing fertility treatments and gaining insight into various birth defects.
As fertility laws are set to be reevaluated and scientific advancements continue to progress, experts are advocating for a reexamination of the 14-day limit.
Dr. Peter Rugg-Gunn from the Babraham Institute in Cambridge explained that the period of embryo development between two to four weeks is often referred to as the “black box” due to limited understanding. Currently, there is no feasible way to study this stage, leading to restricted knowledge. Extending the study of embryos beyond the 14-day limit could potentially have positive outcomes for patients. Therefore, allowing this sooner in the UK would result in earlier benefits for patients.
Possible advantages include identifying reasons for unsuccessful implantation, where the fertilized egg does not successfully attach to the uterine lining resulting in miscarriage, and discovering the sources of congenital heart abnormalities, which occur in approximately 1% of births and are believed to contribute to 40% of prenatal fatalities.
Rugg-Gunn stated that it is crucial for individuals to comprehend the potential advantages. However, they did not explicitly advocate for an increase in the limit as part of the Human Fertilisation and Embryology Authority’s (HFEA) comprehensive plans to update the legislation.
The 14-day limit for embryo cultivation in the UK was initially suggested in the 1984 Warnock report, which addressed the ethical and regulatory aspects of IVF technology. This rule has been in effect since 1990 and prohibits the growth of embryos beyond 14 days of development or before the formation of the primitive streak, which establishes the body’s axis. It was designed to strike a balance between the potential medical advancements of research and the unique status of human embryos.
In 1990, the limit was only a concept as researchers were unable to sustain embryo growth in a laboratory for more than a few days. However, within the last five years, this has shifted and a greater number of labs globally have the ability to accurately simulate development until the legal restriction.
Rugg-Gunn stated that we have reached a stage where these experiments are likely achievable. Continuing research would likely lead to new knowledge that could greatly benefit health, especially in understanding the reasons behind recurring miscarriages.
After the 14th day, gastrulation takes place, a significant process in which the embryo transforms from a basic cluster of cells into three separate tissue layers that establish a rudimentary body structure. Rugg-Gunn stated, “This is a crucial stage in development, but it has not been thoroughly examined or observed until now.”
The embryo is typically inserted into the endometrium (womb lining) between day six and 12. However, this process can continue and potentially result in complications after day 14, which is often cited as a frequent cause of failed IVF treatment.
According to Prof Kathy Niakan, a developmental biologist from the University of Cambridge, during pregnancy there is a special immunological interaction that occurs. This raises the intriguing question of why, in certain instances, the maternal and fetal cells are unable to coexist without some form of aggression or malfunction.
In the third week, cells continue to specialize and the initial heart cells are created. It is believed that a significant number of congenital heart defects occur during this early stage of growth. Between days 21 and 28, the neural tube (the early form of the central nervous system) develops and closes. Spina bifida results from a failure of the neural tube to close correctly, but the exact process has not been directly observed. Around four weeks, researchers start to gain understanding of development through pregnancy ultrasounds and embryos donated from terminated pregnancies.
There is a debate about whether scientists are exaggerating the potential medical advantages of growing embryos for more than 14 days. Some also question if the ethical justifications for the legal limit have truly shifted.
According to Professor Anna Smajdor, a philosopher at the University of Oslo, limits only hold value if they effectively prevent certain actions. With the ability to perform certain actions, scientists may choose to ignore these limits. This undermines the notion that these limits are moral boundaries that have been thoughtfully determined in collaboration with scientists.
In 1990, it was less understood than it is now that a developing embryo does not possess a fully functioning nervous system at 28 days. However, Smajdor argues that the ethical considerations involved are not solely focused on whether or not the embryo can feel pain. Even without considering religious beliefs, some may believe that embryos hold moral significance due to their potential to develop into human beings. This also has a symbolic aspect to it.
Some argue that due to scientific progress, the responsibility has changed. According to Sarah Norcross, the CEO of Progress Educational Trust, human embryos are a limited and valuable asset. Should scientists be required by law to halt their research on these embryos after 14 days, when there is potential to gain valuable insights and improve understanding of pregnancy loss and illness?
Some people think that the ongoing changes to the legal system signify the need to revisit the topic. Niakan stated that engaging in this conversation does not necessarily lead to a change in the rule, but rather allows for a mutual exchange of ideas regarding potential benefits and risks, and prompts us to consider our stance on the matter.
Source: theguardian.com
