Pregnancy and perinatal outcomes of first-trimester crown-rump length discordance in dichorionic twin pregnancies after in vitro fertilization

Abstract

To evaluate the association between first- trimester crown-rump length discordance and adverse pregnancy and perinatal outcomes in dichorionic twin pregnancies. This was a retrospective cohort study of women with dichorionic twin pregnancies after in vitro fertilization (IVF) at our fertility center with two live fetus scanned between 6+5 and 8 weeks’ gestation during the period 1st January 2015 and 1st January 2017. Study groups were defined by the presence or absence of ≥20% crown-rump length (CRL) discordance at the first-trimester ultrasound scans. Pregnancy outcomes including spontaneous abortion, stillbirth and live birth were compared between discordant and concordant twin pregnancies. Perinatal outcomes (preterm delivery, [PTD], low birth weight [LBW], very low birth weight [VLBW], birthweight discordant, neonatal death and admission in neonate intensive care unit [NICU]) were also assessed. Singleton live deliveries and twin deliveries were analyzed separately. Moreover, fetal anomalies were also evaluated. During the study period we identified 1687 dichorionic twin pregnancies on first-trimester ultrasound, of which1504 met the inclusion criteria. Of the 1504 dichorionic twin pregnancies included, 129 (8.58%) patients were identified as having CRL discordance of at least 20%. CRL discordant twin were more likely to end in one fetal loss before 12 weeks’ gestation (Relative risk= 15.073,95% confidence interval, 10.128-22.431) than were concordant dichrionic twin pregnancies. Discordant twin pregnancies with twin deliveries were at significant higher risk of birthweight discordance (Relative risk=2.192,95% confidence interval, 1.054-4.558). There was no significant difference in perinatal outcomes including PTD, LBW, VLBW, neonatal death and admission to NICU in singleton or twin deliveries. No fetal anomalies were observed in discordant twin pregnancies. Dichorionic twin pregnancies were at increased risk for one fetal loss prior to 12 weeks’ gestation and birthweight discordance, but were not associated with adverse perinatal outcomes and fetal anomalies.