Early onset discordant growth in monochorionic twin gestation

Introduction: Abnormal growth, including discordant growth and intrauterine growth restriction (IUGR), occurs frequently in twin pregnancies and has been associated with increased risk of perinatal morbidity and mortality. Typically this occurs in the second or third trimester. Discordant growth in monochorionic twin pregnancies is probably related with the complications of a shared placenta. It is not clear whether there is increased risk of perinatal morbidity in both discordant twins or only in those with low birth weight. Case report: A 21 year old primigravida with a spontaneous monochorionic twin pregnancy was seen to have a crown-rump length discordance at 8 weeks of gestation (one fetus with 6mm and the other with 12 mm). All routine tests were normal. No major congenital or karyotype abnormalities or evidence of twin to twin transfusion syndrome (TTTS) were detected during follow up examinations. This discrepancy persisted until birth: fetus A was in the 25th percentile while fetus B below the 5th percentile. Umbilical artery flow in both twins remained normal. At 34 weeks, preeclampsia developed and labor induction was performed. The twins had a birth weight of 2195 g and 1415 g (35,5% discrepancy), and an Apgar score of 7 and 10 at 5th minute, respectively. They remain in the neonatal intensive care unit for 29 days, with the larger twin having more complications: transient tachypnea of the newborn, pneumothorax and hyperbilirubinemia. At two years old, they both had a normal development. Discussion: In monochorionic twins with a normal karyotype and no evidence of TTTS, the causes of discordant growth are not always clear. In this case, the occurrence of discordant growth and IUGR did not lead to more complications in the smaller twin