Early Prediction of Small for Gestational Age: The Predictive Role of Pregnancy Associated Plasma Protein-A

Abstract

Introduction: Small for Gestational Age (SGA) is a compelling obstetric adversity with multiple consequences. Early diagnosis, although a challenge, can help blunt the adverse effects. One of the markers is Pregnancy Associated Plasma Protein-A (PAPP-A) which can be an early predictor of SGA. Aim: To find the association of low levels of pregnancy associated plasma protein-A with small for gestational age. Materials and Methods: This prospective observational study was conducted in the Department of Obstetrics and Gynaecology at All India Institute of Medical Sciences, Raipur, Chhattisgarh, India, between June 2018 and September 2019. The demographic profile, PAPP-A Multiples of Median (MoM) levels, complications in pregnancy and birth outcome data of a total of 203 women were noted. For analysis of descriptive and categorical data, IBM Statistical Package for the Social Sciences (SPSS) statistical software version 23.0 was used. Shapiro-Wilk and Kolmogorov-Smirnov tests were performed to assess normality of distribution. Qualitative data were analysed by Chi-square test and categorical data, by Mann-Whitney’s U test. Results: The mean maternal age of the study sample was 27.4±2.23 years. The prevalence of SGA was 18.2%, out of which PAPP-A MoM levels were ≤0.49 in 59.4%. The association between PAPP-A levels and SGA was statistically significant (p-value=0.03) with unadjusted odds ratio of 8.27 (95% CI, 3.78-18.08). Simple logistic regression showed an inverse relationship of PAPP-A with SGA. At the cut-off of ≤0.49 considered in the study, sensitivity was 86.7%, specificity was 54.1%, positive predictive value was 29.5% and negative predictive value was 94.8%. Positive likelihood ratio was 1.88 and negative likelihood ratio was 0.24 and the diagnostic accuracy was found to be 59.9%. Conclusion: An inverse relationship between levels of PAPP-A MoM (≤0.49) and SGA was found in the study. Low levels of PAPP-A MoM can be a useful early predictor of SGA.

Keywords

• early diagnosis
• foetal outcome indicator
• placental biomarkers