Selective intrauterine growth restriction in monochorionic twins or SIUGR is the disproportionate distribution of placental mass between the twins (unequal sharing of the placenta). This factor may result in poor nourishment of one of the twins, resulting in subsequent poor overall fetal growth. Because this problem typically affects only one of the fetuses, the condition is called selective intrauterine growth restriction (SIUGR). SIUGR is estimated to occur in approximately 10% of monochorionic twin pregnancies. Although these pregnancies may show amniotic fluid discordance, they do not meet criteria for twin-twin transfusion syndrome, defined as a maximum vertical pocket of 8 or more cm in one sac and 2 cm or less in the other. Spontaneous demise of the IUGR twin may occur in up to 40% of cases and is associated with up to 40% likelihood of demise of the co-twin, or the co-twin survives, up to 30% likelihood of neurological morbidity. The adverse effects associated with spontaneous demise of the IUGR twin are caused by perimortem feto fetal hemorrhage through patent placental vascular anastomoses. These complications do not occur in dichorionic twins, where there are no vascular anastomoses between the placentas. We have developed a laser surgical technique (selective laser photocoagulation of communicating vessels - SLPCV), which can effectively separate the circulations of two monochorionic fetuses. The purpose of this study is to compare expectant management vs. SLPCV in monochorionic twin pregnancies with selective IUGR and absent end-diastolic velocity in the umbilical artery of the IUGR twin. Patients with IUGR without AEDV will be invited to participate in the trial in an observational arm.

INCLUSION CRITERIA:
1) Gestational age of 16-24 weeks.
2) Sonographic evidence of monochorionic-diamniotic twin pregnancy.
3) Diagnosis of IUGR in one twin (estimated fetal weight at or below the 10th percentile for gestational age).
4) Persistent absent or reverse end- diastolic velocity in the umbilical artery in the IUGR twin. 5) IUGR: Estimated Fetal Weight (g) at or Below the 10th Percentile .

16 weeks less than 121 g
17 weeks less than 150 g
18 weeks less than 185 g
19 weeks less than 227 g
20 weeks less than 275 g
21 weeks less than 331 g
22 weeks less than 398 g
23 weeks less than 471 g
24 weeks less than 556 g

EXCLUSION CRITERIA:
1) Presence of twin-twin transfusion syndrome (TTTS)
2) Presence of major congenital anomalies.
3) Both twins have an estimated fetal weight at or below the 10th percentile for gestational age.
4) Unbalanced chromosomal complement (if known).
5) Ruptured or detached membranes.
6) Placental abruption.
7) Chorioamnionitis.
8) Triplets.
9) Active labor.
10) Placenta previa.