[Perinatal outcome of monochorionic diamniotic twins with selective intrauterine growth restriction]

To evaluate the perinatal outcome of three types of monochorionic diamniotic (MCDA) twins with selective intrauterine growth restriction (sIUGR).

From January 2005 to June 2012, clinical data of 42 pairs of MCDA twins (84 fetuses) with sIUGR and 71 pairs of normal MCDA twins (142 fetuses) in the same period were analyzed retrospectively in the First Affiliated Hospital of Sun Yat-Sen University. Fetuses with sIUGR were classified into three groups based on umbilical artery Doppler flow.There were 25 cases of type I, 11 cases of type II and 6 cases of type III. The perinatal outcome was compared between sIUGR and normal MCDA twins, and among the three types of sIUGR as well. Perinatal outcomes included gestational age at delivery, rate of intrauterine fetal death (IUFD), birth weight, intertwin discordance of birth weight, neonatal death and survival rate at 6 months.

(1) The gestational age of sIUGR at delivery was significantly earlier than the control group [(34±3), (36±2) weeks, respectively], and the rate of IUFD of both fetuses of sIUGR was significantly higher (4.8%, 0, respectively). In the sIUGR group, the average birth weight of large or small twins [(2130±350), (1520±400) g, respectively] was smaller than those in the control group [(2470±500), (2340±460) g, respectively]. The difference was statistically significant (P<0.05, P<0.01, respectively). The intertwin discordance of birth weight in sIUGR group was significantly larger (27.6%) than the control group (4.0%, P<0.01). (2) The gestational age at delivery in type II and type III [(34±5), (34±2) weeks, respectively] was significantly earlier than the control group (P<0.05). The rate of IUFD of both fetuses in type II (18%) was significantly higher than in type I (0) and the control group (0, P<0.05). In sIUGR group, the average birth weight of small twins in type I, type II and type III was (1640±430), (1330±310) and (1500±380) g respectively, all of which were significantly smaller than that in the control group (P<0.05). The average birth weight of small twins in type II was smaller than in type I and the difference was statistically significant (P<0.05). In sIUGR group, the intertwin discordance of birth weight in type I, type II and type III was 24.1%, 34.6%, 31.3% respectively, all of which were significantly larger than that in the control group (4.0%, P<0.05). There were no statistically significant differences of the intertwin discordance of birth weight among the three types of sIUGR (P>0.05). Survival rate at 6 months in type II (64%) was significantly lower than in type I (92%) and the control group (91.5%, P<0.01).

The perinatal outcome of MCDA twins with sIUGR is poor. The outcome is different among the three types of sIUGR, and typeIIis the worst. Type II is associated with a high risk of intrauterine fetal demise. It is important to monitor the intrauterine situation closely.