- Objective: The purpose of this study was to investigate whether maternal serum CA 125 determination in women with uterine bleeding has a prognostic value in the detection of women at risk for delivering a small-for-gestational-age neonate. Study design: The patients population consisted of women with uterine bleeding at a gestational age greater than 20 weeks. Patients with abruptio placentae, placenta previa, fetal distress and history of coagulopathy were excluded. Maternal serum CA 125 was measured at admission. Receiver operating characteristics curve analysis and logistic regression were used for statistical purposes. Results: Fifty-nine women were enrolled into the study. Six of these had a small-for-gestational-age neonate, 8 had premature rupture of membranes and 33 delivered preterm. No relationship was found between maternal serum CA 125 concentrations and preterm delivery or PROM. Women who delivered a small-for-gestational-age infant (10.1%) had lower maternal serum CA 125 levels than those who delivered an appropriate-for-gestational-age infant (P < 0.02). Patients with uterine bleeding and serum CA 125 ≤ 10 U/ml had a twofold risk to deliver a small-for-gestational-age neonate. Sensitivity, specificity, positive and negative predictive values were 66.6%, 79.2%, 26.6% and 95.4%, respectively. Conclusion: Our results show that a decreased maternal serum CA 125 concentration in women with uterine bleeding during the second half of pregnancy is of prognostic value in identifying those who will deliver a small-for-gestational-age infant.