Researchers at the University of Cambridge identified the protein isthmin-2 (ISM2) as a predictor for preeclampsia and fetal growth restriction, based on a study published in Nature Medicine in 2026. ^[1] Preeclampsia affects up to one in 14 pregnant women globally and can lead to stillbirth or maternal death by reducing blood flow through the placenta. ^[2] Fetal growth restriction affects roughly 3% to 10% of pregnancies in high-income countries and up to one in five pregnancies globally. ^[3] Low circulating levels of ISM2 around three months into pregnancy were the strongest indicator that a pregnancy would develop preeclampsia or fetal growth restriction. ^[4] Professor Gordon Smith, head of the Department of Obstetrics and Gynecology at the University of Cambridge, said early-pregnancy maternal levels of isthmin-2 are much better at predicting complications than existing tests and could enable better identification of at-risk pregnancies, as well as potential treatments such as stimulating ISM2 production in the placenta. ^[5] Dr. Gordon Smith, study leader and head of Cambridge's Department of Obstetrics and Gynaecology, stated that low circulating levels of the protein isthmin-2 (ISM2) about three months into pregnancy were the strongest indicator of future preeclampsia or fetal growth restriction. ^[6] Fetal growth restriction affects up to 10% of pregnancies in high-income countries and up to one in five pregnancies globally, making it a leading cause of complications in newborns. ^[7]