Aim: We aimed to investigate whether first trimester ultrasound and biochemical markers of aneuploidy were related to birth weight and to determine the predictive role of these parameters for small for gestational age (SGA) and large for gestational age (LGA) newborns. Material and Method: 1356 women with singleton pregnancy who had undergone first-trimester aneuploidy screening by nuchal translucency (NT)thickness, maternal serum free beta-human chorionic gonadotropin (f beta-hCG), and pregnancy-associated plasma protein-A (PAPP-A) were retrospectively included. Newborns with a birth weight of <= 10th percentile were defined as SGA and >= 90th percentile as LGA, respectively. Results: Serum PAPP-A level was significantly but weakly (r=0.168: p=0.011) correlated to birth weight whereas maternal serum f beta-hCG levels and NT measurements were not significantly correlated. A single PAPP-A level of <0.795 MoM predicted SGA newborn with a sensitivity of 73.9%, specificity of 63.1%, PPV of 18.5%, NPV of 95.5%, and accuracy of 64.2%. On the other hand, a PAPP-A level of 1.005 MoM was identified as the optimal cut-off point for the prediction of SGA newborn with a sensitivity of 61.0%, specificity of 62.7%, PPV of 26.6%, NPV of 87.9%, and accuracy of 62.4%. Discussion: First-trimester PAPP-A levels may contribute to the prediction of birth weight. However, due to low sensitivity, it is not a clinically relevant screening test for prediction of SGA or LGA newborn.