Relationship between first-trimester serum placental protein-13 and maternal characteristics, placental Doppler studies and pregnancy outcome.

OBJECTIVE: To examine potential correlations between maternal serum placental protein-13 (PP-13) and first trimester maternal and placental factors, and to evaluate the association of this marker with adverse pregnancy outcome.

METHODS: Serum samples from prospectively enrolled patients between 11 and 13 weeks and 6 days were analyzed for PP-13 using an ELISA assay. The relationships between maternal serum PP-13 levels and gestational age, maternal age, ethnicity, parity, smoking status, body mass index (BMI), mean arterial blood pressure, uterine and umbilical artery Doppler parameters were examined. The association between first-trimester PP-13 levels and subsequent pre-eclampsia and delivery of a small for gestational age (SGA) neonate was also investigated, after excluding patients who received aspirin.

RESULTS: In 908 patients, PP-13 levels ranged from 8.0 to 537.5 pg/mL. A significant negative correlation was identified between PP13 and BMI (Spearman rho -0.20, P<0.0001). Smoking significantly decreased PP-13 (P<0.01). No relationship was identified with the other parameters. In a subgroup of 668 low-risk patients who did not receive aspirin, PP-13 levels were not associated with development of pre-eclampsia, SGA or the combination of them.

CONCLUSION: First-trimester PP-13 levels are significantly correlated with BMI and smoking. These correlations appear independent of uterine and umbilical artery resistance. In low risk patients, PP-13 levels fail to predict the risk for pre-eclampsia or SGA.