OBJECTIVE: To assess the association between placental biomarkers (placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1)/PlGF ratio) and fetoplacental Dopplers - Umbilical Artery Pulsatility Index (UA PI) and Uterine Artery Pulsatility Index (UtA PI) in various combinations for the likelihood of preterm birth (PTB) in women with fetal growth restriction (FGR). METHODS: A prospective cohort study of pregnancies complicated by FGR. Maternal serum PlGF levels, sFlt-1/PlGF ratio, UA PI and UtA PI were measured at 4-weekly intervals from recruitment to delivery. Harrell's concordance statistic was used to evaluate various combinations of placental biomarkers and fetoplacental Dopplers to ascertain the ideal combination to predict PTB (<37 weeks). Multivariable Cox regression was used as time-varying covariates. RESULTS: There were 320 pregnancies in the study cohort - 179 (55.9%) were FGR and 141 (44.1%) were AGA. In the FGR cohort, both low PlGF levels and elevated sFlt-1/PlGF ratio significantly affected time to PTB. Low PlGF was a better predictor of PTB than either sFlt-1/PlGF ratio or combination of PlGF and sFlt-1/PlGF ratio (Harrell's C 0.81, 0.79, 0.75 respectively). Similarly, although both UA PI and UtA PI >95th centile for gestation significantly affected the time to PTB, in combination, they were better predictors than either measure alone (Harrell's C 0.82, 0.75, 0.76 respectively). The predictive utility was highest when PlGF <100ng/L, UA PI and UtA PI >95th centile was combined (Harrell's C 0.88) (HR 32.99 95% CI 10.74, 101.32). CONCLUSIONS: Low maternal PlGF levels (<100ng/L) and abnormal fetoplacental Dopplers (UA PI and UtA PI >95th centile) in combination have greatest predictive utility for PTB in pregnancies complicated with FGR and may help guide clinical management of these complex pregnancies. This article is protected by copyright. All rights reserved.