Background: Low birth weight (LBW) can be an important adverse neonatal outcome in terms of morbidity and mortality. The aim of this study is to investigate the screening effectiveness of first-trimester low pregnancy-associated plasma protein A (PAPP-A) and high serum thyroid-stimulating hormone (TSH) and the combination of both markers for predicting LBW.
Methods: We performed a retrospective cohort study of women undergoing first-trimester assessment in our center. We considered low PAPP-A as < 5th percentile for gestational age. High serum TSH was defined as > 2.5 mU/L, according to the American Thyroid Association (ATA) recommendation. Receiver-operating characteristic (ROC) curves were plotted to evaluate screening performance. Multivariate logistic regression was accomplished to calculate adjusted risks to identify the association between both parameters with LBW.
Results: Overall, 4,396 women met the inclusion criteria. Of these, 277 (6.3%) delivered a LBW baby. The use of either low PAPP-A or high TSH yielded the highest sensitivity (21.1%) with a specificity of 85.7%. Combining both markers showed an increased association (adjusted OR 9.07 [95% CI 3.34 - 24.6]) at the expense of a significant reduction in sensitivity (7.8%).
Conclusions: First-trimester low PAPP-A is associated with LBW at delivery. Neither of these biomarkers or their combination are acceptable predictors to be clinically useful tools for LBW.