347: Are first trimester growth restriction (FGR) and low pregnancy-associated plasma protein A (PAPP-A) efficient for predicting small for gestational (SGA) at delivery?

Recent studies suggest that early FGR and low PAPP-A is associated with growth abnormalities in late pregnancy. Our objective is to evaluate the efficiency of first-trimester FGR, low PAPP-A, and their combination for predicting SGA at delivery. A retrospective cohort of pregnancies with reliable dating based on last menstrual periods and consistent with first-trimester ultrasounds was identified. Multiple gestations, aneuploidy, and major structural anomalies were excluded. Fetal crown-rump lengths (CRL) were measured at 10-14 weeks gestation and converted to gestational age (GA) adjusted Z-scores. Different CRL z-score thresholds(< −1, −1.5, −2, and −2.5 SD) were evaluated as first-trimester FGR associated with SGA. Maternal PAPP-A was obtained at the time of the first-trimester aneuploidy screen. Low PAPP-A was defined as levels(multiples of the median)<5% percentile for GA. Receiver-operating characteristics (ROC) curves were used to identify the optimal definitions of early FGR associated with SGA and to compare screening efficiencies. Multivariable analysis was used to control for confounders. Among 3329 pregnancies meeting the inclusion criteria 185(5.6%) infants were SGA. CRL z- score< −1.0 SD was identified as the optimal definition of early FGR associated with SGA(AOR 1.78[95% CI 1.24-2.56]) with a sensitivity and specificity of 23.6% and 85.6%, respectively. Low PAPP-A was also associated with SGA(AOR 2.96[95% CI 1.82-4.83]). Using low PAPP-A combined with first-trimester FGR, the association was modestly increased(AOR 4.23 [CI 1.37-13.03]) at the expense of significantly reduced sensitivity(3.13%). However, when either low PAPP-A or first trimester FGR was considered as screen positive, the association persisted(OR 2.17[CI 1.57-3.00]) with improved sensitivity(33%) and only a slight decrease in specificity(82.1%). Our data confirm that first-trimester FGR and low PAPP-A are associated with delivery of an SGA infant. Combination of these two parameters results in a modest improvement in screening efficiency for SGA compared to either of them alone.Table 1Association between first trimester FGR and low PAPP-A with SGA at deliveryPrediction CriteriaSGA n (%)Sensitivity (%)Specificity (%)Area under the ROC CurveAdjusted Odds Ratio [95% CI]CRL z-score < −1 (n=590)43(7.2)23.685.60.551.78 [1.24-2.56]PAPP-A < 5% (n=202)22(10.9)12.295.70.542.96 [1.82-4.83]Either CRL z-score < −1 or PAPP-A < 5% (n=759)61(8.0)33.082.10.582.17 [1.57-3.00]Both CRL z-score < −1 and PAPP-A <5% (n=33)4(12.1)3.1399.20.514.23 [1.37-13.03] Open table in a new tab