A Cochrane review of universal late-pregnancy ultrasound has been highly influential in guiding UK practice, concluding that it does not improve outcome. However, the meta-analysis combines trials that used diverse definitions of screen positive, were designed in the absence of high-quality data on diagnostic effectiveness and did not couple screening to an effective intervention. Moreover, even if the trials had combined a highly effective screening test with a highly effective intervention, the sample size was 15% of that required to study perinatal death. It is not known whether universal late-pregnancy ultrasound confers benefit on the mother or baby. TWEETABLE ABSTRACT: Despite >50 years of research, we do not know whether universal late-pregnancy ultrasound confers benefit on the mother or baby.