Predicting SGA neonates using first-trimester screening: influence of previous pregnancy's birthweight and PAPP-A MoM.

Objective: Investigating the proportions of anamnestic and biochemical variables of the previous and current pregnancies for the prediction of small for gestational age (SGA) neonates in the current pregnancy.
Methods: In this observational retrospective study, 45 029 pregnancies were examined, including 3862 patients with more than one pregnancy. Odds ratios for SGA using anamnestic parameters and pregnancy-associated plasma protein A (PAPP-A) values from all pregnancies were estimated by using a logistic regression model.
Results: There were 2552 (5.7%) SGA neonates. Two threshold PAPP-A values were identified at 0.15 MoM and 0.33 MoM with probabilities for SGA of 23% and 17%, respectively. A previous SGA < 10th centile and a current PAPP-A MoM value < 5th centile result in odds ratios of 4.8 (95% CI: 3.5-6.5) and 3.0 (95% CI: 1.8-5.0), respectively. The parameters' combined odds ratio is 14.1 (95% CI: 3.9-50.3) with a number needed to screen of ten for one SGA neonate at a detection rate of 37%.
Conclusion: Information on previous pregnancies affected by SGA and a current pregnancy's low PAPP-A value are reliable predictors for a SGA delivery. First-trimester biochemical analysis should be maintained to detect women at risk for delivering a SGA neonate.