First-Trimester Biochemistry and Outcomes in Twin Pregnancy

OBJECTIVE: To examine the relationship between levels of first-trimester serum analytes used in aneuploidy risk assessment and obstetric outcomes in twin pregnancy. STUDY DESIGN: Twin pregnancies undergoing first trimester risk assessment from 2003 to 2005 were identified. Pregnancy-associated plasma protein A (PAPP-A) and free beta-human chorionic gonadotropin (beta-hCG) were measured at 9-14 weeks. The association between extreme biochemical values (<5th and >95th percentile) and adverse outcomes was examined. Fisher's exact test and Mann-Whitney U were used for comparison. RESULTS: A total of 326 pregnancies were included. Median maternal age was 35 years. Median gestational age at delivery was 36 weeks. There were no significant associations between extreme free beta-hCG or high PAPP-A values and the rates of any adverse outcomes. Low PAPP-A (<0.52 multiples of the median) was associated with higher rates of discordant growth (50% vs. 13%; p = 0.001) and hypertensive disorders of pregnancy (41.2% vs. 15.5%, p = 0.01). CONCLUSION: In twin pregnancies, low PAPP-A is associated with discordant growth and hypertensive disorders.(J Reprod Med 2009;54:312-314)