The placenta is a temporary organ that is essential for a healthy pregnancy, normal growth and development of the fetus, and hence birth of a healthy infant. Placental dysfunction increases the risk of pregnancy loss (stillbirth or miscarriage), hypertensive disorders of pregnancy, gestational diabetes, preterm delivery, babies who are born too small or too large, death in the first year of life and cerebral palsy. We do not know how the placenta works. There are methods that can be used on placental tissue (collected after birth) to measure how the placenta works at a molecular level. However, it is not known how well these methods perform in large scale cohort studies like ALSPAC. The advantages of using these methods in cohorts like ALSPAC are that those studies have lots of information on the pregnancy and mother and child's health(which most studies that have used these methods do not). However, it is not easy in cohorts to collect placental tissue with the same rigour that has been used in placental research focused studies. In particular the time between delivery of the placenta and processing is suggested to ideally be 30 minutes, but this is not possible when placenta are being retrieved from hospitals and brought to a University laboratory like BBL. Whether longer time intervals make the measurements unreliable is not known. In this 'proof of concept' grant we will measure placental function at a molecular level by assessing gene expression, DNA methylation, and metabolites in detail using placenta from the ALSPAC-G2 cohort. We will assess how these measures relate to time interval between delivery and initial processing and undertake some preliminary research analyses.