Role of pregnancy-associated plasma protein A (PAPP-A) and human-derived chorionic gonadotrophic hormone (free β-hCG) serum levels as a marker in predicting of Small for gestational age (SGA): A cohort study

BACKGROUND: Small-for-gestational-age (SGA) is one of the most important conditions, which is associated with the risk of perinatal mortality and morbidity. The levels of pregnancy-associated plasma protein A (PAPP-A) and β-human-derived chorionic gonadotrophic (β-hCG) in the first trimester can predict this adverse outcome, considering the controversial nature of studies in this area, this cohort study was conducted to investigate the role of PAPP-A and freeβ-hCG levels for predicting SGA. MATERIALS AND METHODS: In this cohort study, from 16 randomly selected health centers in Isfahan, Iran, 4605 volunteer pregnant women who had performed first-trimester fetal anomalies screening tests were chosen based on the census, from July 2016 to June 2018. The multiples of the median (MoM) PAPP-A <0.4 and MoM β-hCG >3 were considered as abnormal; the samples were followed up after childbirth. The biomarkers' serum levels, relative risk, and odds ratio (OR) of SGA were compared in both SGA and appropriate for gestational age (AGA) groups. RESULTS: In the SGA group, the mean of MOM PAPP-A was significantly lower (0.96 vs. 1.1 with P = 0.001) and MoM βhCG was significantly higher (1.24 vs. 1.15 with P = 0.01) than the AGA group. Odds for SGA in subjects with MoM PAPP-A <0.4 were 3.213; P = 0.001 and for subjects with MoM βhCG >3 reported as 0.683; P = 0.111. CONCLUSION: The results of the study showed that the low levels of PAPP-A would cause 3.213 times increase in the chance of developing SGA and no association between high level of βhCG >3 with SGA. Therefore, low level of the PAPP-A is a warning indicator for SGA.