Scientists have captured the moment a human embryo implants in real time, giving new insight into the earliest stage of pregnancy.

Researchers at the Institute for Bioengineering of Catalonia (IBEC) and Dexeus University Hospital in Spain recorded the process using a 3D model that simulates the uterus.

Footage from two videos shows the process of cell compaction in the embryo and the embryo invading the artificial uterine matrix.

Implantation failure is a major cause of infertility and is responsible for 60 per cent of early miscarriages.

Lead researcher Samuel Ojosnegros said: 'We have observed that human embryos burrow into the uterus, exerting considerable force during the process.

'These forces are necessary because the embryos must be able to invade the uterine tissue, becoming completely integrated with it. It is a surprisingly invasive process.'

The embryo uses both special enzymes and physical force to move through thick tissue and connect with the mother's blood vessels.

Ojosnegros added: 'The embryo opens a path through this structure and begins to form specialised tissues that connect to the mother's blood vessels in order to feed.'

Co-author Amelie Godeau said the embryo also changes its surroundings by pulling and rearranging the uterine tissue. This suggests that natural contractions of the uterus might affect how well implantation works.

The new lab model allowed the team to watch this process live and study the forces involved. They found that human embryos fully push through tissue, unlike mouse embryos, which get wrapped by the uterus instead.

Co-first author Anna Seriola said: 'Our platform has allowed us to quantify the dynamics and mechanical footprint of this complex process in real time.'