Up to 1 in 4 New Zealand couples have trouble conceiving and many seek help trying to start a family. Often their treatment will be IVF, but success rates remain low. During IVF multiple embryos are produced, and the decision on which embryo to select for transfer back into the woman is key to its success. However, current methods are subjective and imprecise. In this proposal, we aim to develop a new methodology to identify embryos that are of high quality and likely to implant based on the molecular signature of the extracellular vesicles (EVs) that the embryos secrete into the embryo culture media as they grow in vitro. This new technology will drastically change the way that embryos are selected for transfer, leading to improvements in success rates and a decrease in the time to pregnancy in women undertaking IVF.