Fetal growth restriction (FGR) is the major single cause of stillbirth 1 and is also associated with neonatal morbidity and mortality 2,3 , impaired health and educational achievement in childhood 4,5 and with a range of diseases in later life 6. Effective screening and intervention for FGR is an unmet clinical need. Here, we performed UPLC-MS/MS metabolomics on maternal serum at 12, 20, and 28 weeks of gestational age (wkGA) using 175 cases of term FGR and 299 controls from the POP study, conducted in Cambridge, UK, to identify predictive metabolites. Internal validation using 36 wkGA samples demonstrated that a ratio of the products of the relative concentrations of two positively associated metabolites (1-(1-enyl-stearoyl)-2-oleoyl-GPC and 1,5-anhydroglucitol) to the product of the relative concentrations of two negatively associated metabolites (5-androstan-3,17-diol disulfate and N1,N12-diacetylspermine) predicted FGR at term. The ratio had approximately double the discrimination as compared to a previously developed angiogenic biomarker 7 , the sFLT1:PlGF ratio (AUC 0.78 versus 0.64, P=0.0001). We validated the predictive performance of the metabolite ratio in two sub-samples of a demographically dissimilar cohort, Born in Bradford, conducted in Bradford, UK (P=0.0002). Screening and intervention using this metabolite ratio in conjunction with ultrasonic imaging at around 36 wkGA could plausibly prevent adverse events through enhanced fetal monitoring and targeted induction of labor. A large proportion of adverse events associated with FGR are unrelated to maternal risk factors 8 and this has motivated research on screening for FGR. However, given that the primary intervention for FGR is early delivery, screening and intervention could cause harm by iatrogenic prematurity in false positives 9. This may explain why the most promising approach to screening for FGR, namely, universal ultrasound, does not result in better outcomes 10. Consequently, the primary method of screening for FGR in low risk women in the USA, UK and many other countries remains clinical examination, such as measurement of the symphyseal-fundal height 11. We have previously argued that one approach to the current impasse is to focus initial efforts on screening and intervention at term 12. One third of all stillbirths occur at term and infants with a birth weight <3 rd percentile at term

Background Pre-term pre-eclampsia is a major cause of maternal and perinatal morbidity and mortality worldwide. A multi-centre randomized–controlled trial has shown that first-trimester screening followed by treatment of high-risk women with aspirin reduces the risk of pre-term pre-eclampsia. However, the biomarkers currently employed in risk prediction are only weakly associated with the outcome. Methods We conducted a case–cohort study within the Pregnancy Outcome Prediction study to analyse untargeted maternal serum metabolomics in samples from 12, 20, 28 and 36 weeks of gestational age (wkGA) in women with pre-eclampsia delivering at term (n = 165) and pre-term (n = 29), plus a random sample of the cohort (n = 325). We used longitudinal linear mixed models to identify candidate metabolites at 20/28 wkGA that differed by term pre-eclampsia status. Candidates were validated using measurements at 36 wkGA in the same women. We then tested the association between the 12-, 20- and 28-wkGA measurements and pre-term pre-eclampsia. We externally validated the association using 24- to 28-wkGA samples from the Born in Bradford study (25 cases and 953 controls). Results We identified 100 metabolites that differed most at 20/28 wkGA in term pre-eclampsia. Thirty-three of these were validated (P &lt; 0.0005) at 36 wkGA. 4-Hydroxyglutamate and C-glycosyltryptophan were independently predictive at 36 wkGA of term pre-eclampsia. 4-Hydroxyglutamate was also predictive (area under the receiver operating characteristic curve, 95% confidence interval) of pre-term pre-eclampsia at 12 (0.673, 0.558–0.787), 20 (0.731, 0.657–0.806) and 28 wkGA (0.733, 0.627–0.839). The predictive ability of 4-hydroxyglutamate at 12 wkGA was stronger than two existing protein biomarkers, namely PAPP-A (0.567, 0.439–0.695) and placenta growth factor (0.589, 0.463–0.714). Finally, 4-hydroxyglutamate at 24–28 wkGA was positively associated with pre-eclampsia (term or pre-term) among women from the Born in Bradford study. Conclusions 4-hydroxyglutamate is a novel biochemical predictor of pre-eclampsia that provides better first-trimester prediction of pre-term disease than currently employed protein biomarkers.