Maternal serum placental protein 13 at eleven to thirteen weeks in chromosomally abnormal pregnancies.

OBJECTIVE To investigate whether the maternal serum concentration of placental protein 13 (PP13) is altered in chromosomally abnormal pregnancies and to examine the potential value of this placental protein in screening for aneuploidies at 11-13 weeks. METHODS The maternal serum concentration of PP13 at 11-13 weeks was compared in 536 euploid and 134 aneuploid pregnancies (trisomy 21: n = 49; trisomy 18: n = 28; trisomy 13: n = 19; Turner syndrome: n = 28; triploidy: n = 10). RESULTS Serum PP13, expressed as multiples of the median (MoM) of the euploid group, was not significantly different in trisomy 21 (1.12 MoM) pregnancies, but the levels were decreased in trisomy 18 (0.75 MoM), trisomy 13 (0.65 MoM), Turner syndrome (0.61 MoM) and triploidy (0.19 MoM). In both euploid and aneuploid pregnancies there was a significant association of serum PP13 with both serum pregnancy-associated plasma protein A (PAPP-A) and free beta-human chorionic gonadotropin (beta-hCG; p < 0.0001 for both). Logistic regression analysis demonstrated that the addition of serum PP13 did not improve the prediction of trisomy 13 and 18 provided by a combination of maternal age, nuchal translucency, and serum free beta-hCG and PAPP-A. CONCLUSION The measurement of maternal serum PP13 at 11-13 weeks does not improve the performance of screening for aneuploidies achieved by current algorithms.