Embryos in pregnancies that end in miscarriage take longer to develop in the womb than those in pregnancies that result in live births. researchers in The Netherlands have been able to look at the way embryos develop while pregnancies are ongoing. They used state-of-the-art imaging technology, including 3D ultrasound with high resolution transvaginal probes and virtual reality techniques, to create 3D holograms of the embryo. What was found was that the first ten weeks of the pregnancy, embryos in pregnancies that end in a miscarriage took four days longer to develop than babies that did not miscarry. Also it was found that the longer it takes for an embryo to develop, the more likely it is to miscarry. The researchers used virtual reality to create holograms to look at the embryos’ development and they compared the morphology or formation against established stages of embryo development, known as the Carnegie Stages. The Carnegie stages of embryonic development cover the first ten weeks of gestation and run from 1 to 23. Compared to an ongoing pregnancy, a pregnancy ending in a miscarriage was associated with a lower Carnegie stage and the embryo would reach the final Carnegie stage four days later than an embryo from a pregnancy that resulted in a healthy baby. A delay in Carnegie stage increased the likelihood of a miscarriage by 1.5% per delayed stage. Therefore, an association between miscarriage and a delay in the early development of the embryo was seen.