When eggs do not mature, fertilisation repeatedly fails, or embryos stop developing during IVF, the question is often the same: why is this happening? A new diagnosis of OZEMA, meaning oocyte, zygote and embryo maturation arrest, brings together difficulties from an immature egg to a fertilised egg or an early embryo whose development stops.
Although the terminology may be unfamiliar, these experiences have been recognised by fertility teams for many years. IVF has allowed us to observe stages of reproduction that would otherwise remain unseen. What is changing is our understanding of the biology, including the discovery that, for some people, a specific genetic alteration can explain repeated difficulties. Genes help control egg maturation, fertilisation and the earliest stages of embryo development. Alterations in genes from egg and sperm providers can disrupt these processes, even when a person is otherwise healthy.
However, a similar pattern in the laboratory does not mean everyone has the same underlying cause. For some people, several genetic influences may act together, alongside biological and environmental factors, rather than there being one identifiable gene responsible. How these combinations contribute to an individual’s difficulties remains incompletely understood. An environmental contribution should not be taken to mean that someone has caused their infertility or could necessarily prevent it.
Where there is a repeated or marked pattern of difficulty, selected genetic testing may help explain why treatment has been unsuccessful. A clear finding can support a more informed discussion about future treatment, the likelihood of recurrence and, where relevant, implications for the wider family. Testing also has limitations. It may find no explanation, or identify a genetic alteration whose significance is uncertain, and a negative result does not exclude a genetic contribution.
An explanation may be valuable even when it does not provide a solution that overcomes the problem. For some people, a diagnosis may support consideration of a different treatment pathway or a choice to continue IVF cycles, understanding that their chances may be lower. IVF treatment cycles are not always identical; a poor outcome in one cycle does not by itself establish a persistent genetic disorder. Equally, changing a treatment protocol may not overcome a confirmed genetic cause. Both the pattern over time and the specific findings matter.
OZEMA provides useful language for describing a group of fertility difficulties, but it cannot tell us the cause or the prognosis on its own. The underlying causes can be very varied. Genetic counselling can help individuals and couples understand what is known, what remains uncertain and which choices fit their circumstances and wishes.
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