Prevalence of cranial scan abnormalities in preterm twins in relation to chorionicity and discordant birth weight.

The purpose of this study was to determine the incidence of ultrasonographically detected cerebral white matter lesions (WMLs) in preterm twins at birth in relation to chorionicity, discordant weight and twin-twin transfusion syndrome (TTTS). In this retrospective study, perinatal, neonatal, and cranial scan data of 85 monochorionic (MC) and 94 dichorionic (DC) twin pregnancies (341 infants) delivered between 24 and 34 weeks of gestation were collected. Data were analysed according to chorionicity, discordant birth weight (>20%), single intrauterine death and TTTS. The cerebral WML was seen in 14% of preterm twins. Monochorionic infants had higher risks of WML than DC twin (odds ratio 7.1; 95% CI 3.28-15.8). In MC group, discordant weight (37%), TTTS (38%), single intrauterine death (67%) had higher incidence of cerebral WML than concordant weight infants (7%). Similarly, incidence of WML was higher in DC discordant compared with concordant weight infants (13% versus 2%; P < 0.05). Monochorionic infants had a seven-fold higher incidence of cerebral WML than DC infants. Discordant birth weight, TTTS and survivor of co-twin demise are an independent risk of cerebral white matter lesion.