This APP and the early pregnancy models were developed by Imperial College London in collaboration with KU Leuven. Assessing women in early pregnancy often involves repeating ultrasound scans at an interval. The Early Pregnancy app allows clinicians to conveniently calculate chance of viability in order to appropriately manage patients expectations (Bottomley et al, Hum Reprod 2013;28:68-76; National Institute for Health and Care Excellence, Clinical Guideline 154, www.nice.org.uk/guidance/cg154/). The APP also includes a model based on measurements of serum hCG and progesterone that predicts the probable outcome for pregnancies of unknown location (PUL), so clinicians can decide if they are at low of high risk of complications in order to arrange appropriate follow up (Van Calster, Bobdiwala et al, in preparation).