The ACOG has long-held that shoulder dystocia is “unpreventable and unpredictable”. Nonetheless, as it is a devastating obstetrical occurrence, researchers have attempted to identify a reproducible mathematical formula using ultrasonographic, anthropometric factors to better predict it. What is the data behind these math models? Does the ACOG recognize their use? What is their positive predictive value? In this episode, we will examine the data – going back 40 years – and we will end the episode with the current stance from the ACOG regarding these mathematical calculations for shoulders dystocia prediction.