Discordant twins and Selective Intrauterine Growth Restriction (sIUGR): A case report

Birth weight discordance, defined as a significant weight differences between twins, has affected approximately 16% of twin pregnancies. Possible causes of discordant twins include twin to twin transfusion syndrome(TTTS), selective intrauterine growth restriction (sIUGR), placental insufficiency in one twin, different genetic growth potential in dizygotic twins, maternal problems, and infection. We presented a case of dichorionic diamniotic discordant twins after in vitro fertilization with one embryo transfer, which developed discordant twins and one selective intrauterine growth restriction (sIUGR) during third trimester. A 35-year-old woman, G3P0SA2, conceived through IVF and had single-embryo transfer, presented with twin pregnancy at 36+4/7 weeks of gestation. Estimated fetal body weight (EFBW) discordance of the twins(2600/1800 grams) was found, favored twin-to-twin transfusion syndrome. Thus, she was admitted for a scheduled cesarean section. After cesarean section delivery, the twin babies were ad-mitted to our NICU(Neonatal intensive care unit) for further survey and management. Weight discordance (Discordant weight of twin growth) occurs in about 16% of twin pairs. Factors that might cause the fetal weight discordance included use of Assisted Reproductive Technology (ART), monochorionic twins, congenital fetal infection, placenta sharing of twins. Our case was conceived through IVF, with 43% difference in the twins body weight. We concerned about serious fetal complications such as Selective intrauterine growth restriction (sIUGR) or Twin-to-twin transfusion syndrome(TTTS). Fortunately, ultrasound and follow-up examination showed no significant abnormality of the twins. Previous studies suggested that regular prenatal ultrasound evaluation may be beneficial to early detection of discordant weight of twins. However, the optimal timing of delivery had not been recommended due to limited data. The incidence of monozygotic twins had increased due to the increased use of ART, which may lead to some fetal complications such as having discordant twins. Weight discordance in twins may contribute to a higher risk of IUFD and other fetal complications. With the assistance of ultrasound, we can diagnose discordant twins at an earlier gestational age and detect its causing factors.