The POP Study was a prospective cohort study investigating the possible causes and predictors of adverse pregnancy outcomes. The study included over 4,000 first-time pregnant (nulliparous) women who attended The Rosie Hospital (Cambridge, UK) for their dating ultrasound scan between 2008 and 2012. The women had serial ultrasound scans throughout pregnancy and provided blood samples at recruitment, 20, 28 and 36 weeks gestational age. After delivery, biopsies of the placenta, placental membranes, umbilical cord, and cord blood were collected. A new longitudinal follow-up study of the cohort began in 2020 under the name POPStar (Pregnancy Outcome Prediction Study: transgenerational and adults review) and tracked the long-term health and development of the children and the mothers through linkage with routinely collected data.