127: Aneuploidy screening analytes and adverse outcomes in twin gestations

Abstract

To evaluate the association between genetic screening serum analytes and adverse pregnancy outcomes in twin gestations We performed a retrospective cohort study of twin gestations with available serum analytes who delivered at a tertiary care hospital from November 2009 to April 2017. Monoamniotic twins and antenatally confirmed fetal genetic anomalies and neural tube/abdominal wall defects were excluded. Data was collected by manual chart review by study investigators. Pregnancy associated plasma protein (PAPP-A), 1st and 2nd trimester human chorionic gonadotropin (hCG), alphafetoprotein (AFP), estriol, and inhibin multiple of the medians (MoMs) were collected, with abnormal levels defined as PAPP-A, 1st trimester hCG, and estriol <5%ile, and AFP, 2nd trimester hCG, and inhibin >95%ile for the cohort. Adverse outcomes were preterm delivery (PTD) < 37 and < 34 weeks gestation, small for gestational age (birthweight <10%ile), and pregnancy-associated hypertensive disease (preeclampsia, gestational hypertension, chronic hypertension with superimposed preeclampsia). Associations between abnormal analyte levels and outcomes, stratified by chorionicity, were calculated using chi-square or Fisher’s exact test. Of 1060 twins delivered during the study interval, 480 (45.3%) had available analytes and met inclusion criteria - 357 dichorionic/diamniotic (di/di) and 123 monochorionic/diamniotic (mono/di). Second trimester analytes were available for all while 249 (51.9%) and 167 (34.8%) women had PAPP-A and 1st trimester beta-hCG respectively. Among di/di twins, elevated AFP (>3.70 MoM) was associated with increased PTD < 34 weeks (44.4 vs 16.5%, P = 0.007) while elevated inhibin (>4.95 MoM) was associated with increased PTD < 37 weeks (94.1 vs 58.8%, P = 0.004). For mono/di twins, elevated inhibin (>6.34 MoM) was associated with an increased PTD < 34 weeks (66.7 vs 24.8%, P=0.04) and hypertensive disease (66.7 vs 21.4%, P=0.03). There were no associations between adverse outcomes and other analytes. Elevated AFP and inhibin in twin pregnancies were associated with increased risks for PTD and pregnancy-associated hypertensive disease, though these associations differed by chorionicity. Such findings may contribute to the ability to identify twin pregnancies at increased risk for adverse outcomes.