In an absolutely massive first, Dutch scientists have built “synthetic” emrbyos that do not require an egg or a sperm, which would raise huge implications for the future of fertility treatments. This stem cell breakthrough, which was detailed in a paper published in the journal Nature, would not be used for cloning people but rather for understanding why pregnancies often fail in early stage implantation.

The embryos were created in a dish and then attached to the womb lining of female mice, where they grew for several days. The discovery could help scientists achieve new breakthroughs in human fertility and understand the process better.

The problem scientists are trying to solve is that miscarriages often take place before women realize they are pregnant as the fertilized egg fails to implant in the womb. Experts have struggled to explain why this happens, so this discovery was key to learning more about the process.