Worldwide, 15% of couples suffer from subfertility, due to the contribution of several factors, such as maintaining a certain lifestyle, nutritional habits and the increasing age at which couples choose to conceive. A possible solution to overcome this subfertility could be the application of assisted reproductive technologies (ART) such as in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Although ART has changed the treatment of subfertility fundamentally and great progress has been made in this field, these techniques are not always successful as the biggest cause of ART failure remains the low implantation rate after embryo transfer. To better understand unsuccessful implantation and placentation in this context, it is crucial to gain insight into the molecular mechanisms in the embryo’s implantation and placentation processes. Many studies have already been done in this area using the mouse as a model system for the development of human embryos, yet several recent papers have revealed interspecies differences, putting a cautionary note on extrapolating findings done in mouse to human. Additionally, other models for human embryonic development such as blastoids, human embryonic stem cells (hESCs) and other mammal models (such as bovine and primate embryos) are considered suboptimal to study these molecular mechanisms during human embryonic development. This creates a necessity to also perform molecular studies directly in human embryos in the future.