Preterm birth affects a significant number of babies born every year, increasing risks of death and life-long disability. Progesterone has been found to halve the odds of preterm birth <34 weeks and neonatal death. Although progesterone is a proven standard medication for pregnant women at risk of preterm birth based on some guidelines (e.g. recommendations by the Current Society for Maternal-Fetal Health Medicine, and National Institute for Health and Care Excellence), few women are receiving this effective prevention. There is an urgent need to improve prevention of preterm birth with progesterone, which the investigators propose to do with an innovative and cutting-edge best-practice alert in electronic medical records (EMRs). Improving care may decrease the risks related to preterm birth, and improve patient experiences and outcomes for women and their babies.