Objective Placental growth factor (PlGF) is a potent angiogenic factor that impacts on early placental vascular development. It was our aim to clarify relationships between PlGF and first-trimester maternal/placental factors that are related to placental development. Methods Prospectively enrolled patients at 11-14 weeks' gestation had serum PlGF measurement by enzyme-linked immunosorbent assay. Results were related to maternal age, parity, race, body mass index, mean arterial blood pressure (MAP), smoking/caffeine use and parameters of placental blood flow resistance. Results In 110 consecutive patients PlGF levels ranged between 1.0 and 176.1 pg/mL, showing a linear relationship with gestational age (GA) (PlGF = (1.4251 x GA) 74.951, r(2) = 0.0765, F = 8.941, P = 0.03). PlGF did not relate to maternal demographics but negatively correlated with MAP (Spearman rho = 0.191, P < 0.05). Bilateral uterine artery notching was associated with lower PlGF (40.7 (range, 1.01-131.6) vs. 51.1 (range, 6.4-176.1) pg/mL; Mann Whitney P = 0.034.). A trend to lower levels was also observed when umbilical artery end-diastolic flow was absent (37.1 (range, 6.8-95) vs. 49.3 (range, 1.01-176.1) pg/mL; P = 0.05). Conclusion PlGF in the first trimester is related to maternal cardiovascular factors and placental Doppler findings that are associated with subsequent placental dysfunction. The utility of this parameter as a first-trimester screening tool on a population basis requires further investigation. Copyright (C) 2010 ISUOG. Published by John Wiley & Sons, Ltd.