First-Trimester Biochemical Markers and Small-for-Gestational-Age Infants Marcadores Bioquímicos do Primeiro Trimestre e Recém-Nascidos Leves para Idade Gestacional

Introduction: Several studies suggested an association between first trimester biochemical markers (PAPP-A and β-HCG) and infants below 10 th percentile. Our goal was to describe this relationship of biochemical markers with small-for-gestational-age fetuses in our population. Material and Methods: Retrospective analytic study of 2 035 pregnant women that underwent first-trimester screening in the period between March 2009 and September 2011. Small-for-gestational-age infants below 10 th percentile were compared with control group (term newborn with birth weight above 10 th percentile). Infants below 3 rd percentile and control group were also compared. Multiple and logistic regression analysis were done with PAPP-A, β-HCG (multiples of the expected normal median) and demographic maternal characteristics (ethnicity, weight and smoker status). Results: This study demonstrated an independent contribution of PAPP-A, maternal weight and smoker status in predicting smallfor-gestational-age infants. For PAPP-A, the odds ratio for small-for-gestational age below 10 th and 3 rd percentile was 2.41 and 3.41, respectively (p < 0.01). For β-HCG, odds ratio below 10 th percentile was 1.70 (p = 0.03) and for birth weight below the 3rd percentile, the odds ratio was 3.22 (p < 0.01). Conclusions: Low levels of PAPP-A and β-HCG (values below 5th percentile of the study population) were associated with an increased risk of small-for-gestational-age infants in the pregnant population included in this study.