191: Is there a difference in placental pathology between twins vs. singleton pregnancies complicated by small for gestational age?

Abstract

We aimed to compare placental lesions and neonatal outcome associated with abnormal fetal growth in dichorionic-diamniotic (DCDA) twins vs. singleton pregnancies complicated by small for gestational age (SGA). The medical records and placental pathologic reports of all singleton pregnancies complicated by SGA, and DCDA twins in which one of the neonates was SGA, delivered between 2008-2017, were reviewed. SGA was defined as birthweight ≤ 10th percentile. Placental diameters were recorded. Placental lesions were classified to maternal and fetal vascular malperfusion (MVM and FVM) lesions (Figure 1). Results were compared between the SGA singleton group and the SGA neonate of the twins group. Composite adverse neonatal outcome was defined as one or more early neonatal complications. As compared to the SGA twins group (n=66), the SGA singleton group (n=500) was characterized by lower maternal age, lower rates of preeclampsia (p=0.010, for both), higher gestational age (34.9±3.1 vs. 37.7±2.6 weeks, respectively, p<0.001) and higher birth weights (2181±451 vs. 1578±455 gr, respectively, p<0.001). Placental villous changes related to MVM lesions and composite placental MVM lesions were more common in the SGA singleton group as compared to the SGA twins (58.6% vs. 31.8%, p<0.001; 62% vs. 45.4%, p=0.040, respectively), see table. By multivariate logistic regression analysis, the SGA singleton group was found to be independently associated with composite MVM lesions (aOR=2.44, 95% CI 1.29-4.61, p=0.006) and villous lesions of MVM (aOR=3.6, 95% CI 1.9-7.0, p<0.001). Composite adverse neonatal outcome was more common in the SGA twins as compared to the SGA singleton group (83.3% vs. 51.2%, p<0.001). Placental MVM lesions are associated with the development of SGA in singleton pregnancies but not in DCDA twins. Development of asymmetric growth in twins is probably related to constrain intrauterine environment rather than abnormal placentation, as in singleton pregnancy complicated with SGA.View Large Image Figure ViewerDownload Hi-res image Download (PPT)