Non-syndromic malformations of the central nervous system in twin pregnancies: diagnostic and other clinical features of importance

Abstract 

Objective

The incidence of central nervous system malformations is higher among twins. Our aim was to summarize information about these malformations in twin pregnancies.

Study design

Based on a sample originating from the biggest genetic centre in Hungary between January 1990 and December 2008, we examined the data of 42 twin pregnancies associated with non-syndromic malformations of the central nervous system.

Results

The involvement of monozygotic fetuses and dizygotic ones of the same gender was found to be 62.5%. Usually only one of the fetuses was affected (57.1%), while the other one was healthy. The male-to-female ratio was 0.75. Identical and fraternal twins were found in 68.4% and 31.6% of the cases, respectively. In the pregnancies of our study the malformation was diagnosed before the 24th gestational week in 90% of the cases. Polyhydramnios (54.8%) was the most commonly associated non-central nervous system malformation.

Conclusion

Our findings suggest that, in addition to placentation and gestational age, the position of the affected fetus with relation to the uterine orifice is of great importance in determining whether selective abortion is an option in deciding about the outcome of pregnancies affected by craniospinal malformation.

Keywords: Twin pregnancy, Genetic counselling, Malformation of the central nervous system, Selective termination of pregnancy, Induced abortion