Summary We have long recognized that there is a link between women's age and their fertility. The biological factors have remained challenging to identify but seems to be driven by the incorrect number of chromosomes, which carry out genetic material, being packaged into the egg. To analyse chromosomes in eggs requires that we can follow them over at least one week before we can take a small sample of the embryo and analyse the chromosome content. In this project, we will use a newly developed equipment that allows us to follow eggs and embryos for the duration of development and correlate this with chromosome errors. We hope to understand how chromosome errors in eggs affect further development after fertilization, how this may explain pregnancy loss and age-related disorders.