The Relationship of PAPP-A and beta-hCG with Adverse Pregnancy Outcomes

Background and Objective: Pregnancy-associated plasma protein A (PAPP-A) is one of the principal markers measured in Down syndrome screening and should be performed between 11 and 14 weeks of gestational age. Human chorionic gonadotropin (hCG) is produced by placenta and is an ideal marker for confirmation of conception. As reported in the literature, maternal serum markers, such as PAPP-A and β-hCG, are related to adverse pregnancy outcomes. Despite vast amount of research, none could prove their high sensitivity in detecting low- or high-risk pregnancy, according to adverse pregnancy outcomes. The current research investigated the relationship between PAPP-A and β-hCG and adverse pregnancy outcomes in the Iranian population. Methods and Materials: This prospective analytical study was performed on singleton pregnant mothers of 18–35 years of age, whose first obstetrical visit was before 14 weeks of gestational age, at the health care centers of Qazvin province, Central region of Iran, during years 2016–2017. All the participants were referred to the reference laboratories for evaluation of PAPP-A and β-hCG at the age of 11–13 weeks and 6 days using enzyme-linked immunosorbent assay (ELISA). In each case, pregnancy outcome was followed up and fetal birth weight was recorded. Abortion before 22 weeks of gestational age, preeclampsia, preterm birth, and fetal weight (g) were charted in the checklist. Data were analyzed using SPSS 20 software and The significance level was defined by p<0.05. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the test were measured by calculating the area under the curve (AUC) of receiver operating characteristic curve (ROC).Results: 994 pregnant females with mean age of 27.73±6.12 years participated in this research. The mean serum level of PAPP-A and β-hCG was 1.10±0.69 and 1.09±0.8 MoM, respectively. Finally, we recorded 899 (90.44%) term birth, 18 (1.81%) abortions, and 77 (7.74%) preterm births. Preeclampsia occurred in 73 (7.34%) cases. PAPP-A had a significant relationship with the incidence of preeclampsia, preterm birth, and fetal low birth weight (P<0.001 for each). However, this relationship with abortion was not significant (P> 0.05) and β-hCG indicated no relationship with the mentioned adverse pregnancy outcomes (P> 0.05). According to ROC, data analysis proved PAPP-A could predict preeclampsia with 81% sensitivity, 74% specificity, 23.6% PPV, and 97.5% NPV (AUC =0.797, P<0.001), low birth weight with 71.1% sensitivity, 70% specificity, 13.4% PPV, and 97.1% NPV (AUC: 0.717, P<0.001) and preterm labor with 67.4% sensitivity, 67.5% specificity, 84.92% PPV, and 95.88% NPV (AUC: 0.712, P<0.001). Conclusion: The result of this study revealed that lower PAPP-A and β-hCG levels could be predictive factors in preterm labor and lower PAPP-A levels would be useful in low birth weight and preeclampsia prediction. Also, this study indicated that PAPP-A measurements could be a screening test for adverse pregnancy outcomes, such as preeclampsia, low birth weight, and preterm labor.

Keywords:

PAPP-A , beta-hCG , Preeclampsia , Abortion , Preterm Labor , Low Birth Weight