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Indian Pediatr 2010;47: 343-344 |
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Congenital Malformations in Twins: Effect of
Chorionicity and Zygosity |
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Priyanka Gupta, MMA Faridi and Geeta Dev*,
From the Division of Neonatology, Department of
Pediatrics; and *Department of Pathology;
University College of Medical Sciences, Delhi 110 095, India.
Email: [email protected]
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Abstract
Twins suffer a high risk of congenital malformations
but the data from our region is scanty. In this study, 133 twin pairs
(266 twin babies) were studied and a 3.4% incidence of malformations was
seen without gender preference. There was no association of chorionicity
and zygosity with the risk for having congenital malformations.
Keywords: Chorionicity, congenital malformations, India,
twins, zygosity.
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T
he incidence of congenital
malformations in twins ranges between 2% to 4.6% that is significantly
higher than that in singletons(1-4). Monozygotic twins are reported to be
more prone for malformations than dizygotic twins(2,5,6).
We conducted this study to determine the pattern of
congenital malformations in twins born in our hospital over a 9 month
period (January to September 2006). Gross congenital anomalies were
recorded within 6 hours of birth by detailed clinical examination in all
successively delivered
³23
weeks twin babies, whether stillborn or live-born. Radiological and
autopsy examinations were carried out as and where indicated. All live
twin babies stayed for 7 days in the NICU/ postnatal ward/ lying-in ward
as per the unit protocols. They were examined daily and observed carefully
for any fresh signs/symptoms. Zygosity was determined with the help of
sex, placental chorionicity and 7 blood group phenotypes(7).
During the study period, 7147 mothers ( ³23
wk) delivered; of whom there were 133 twin pairs. The rate of twinning was
1 in 53.7 pregnancies. Out of 133 twin placentae, 117 were dichorionic and
16 were monochorionic. Zygosity could be determined in 110 pairs; 81
dizygotic and 29 monozygotic twins(7).
Nine (3.4%) twin babies had congenital anomalies. One
pair had acardiac twin (TRAP sequence) which was confirmed on autopsy. A
possibility of hydrolethalus syndrome was kept in another baby (cluster of
anomalies including gross hydrocephalus, cleft lip/palate and polydactyly).
Other malformations seen were duodenal atresia (n=1), inguinal
hernias (n=2) and congenital-talipes-equinovarus (n=4). All
these 9 malformed babies were live-born, except for the acardiac twin.
The incidence of congenital malformations in female and
male twin babies was 3.1% (4/129) and 2.9% (4/136) respectively (P=0.07).
Malformations were present in 3.1% (1/32) monochorionic and 3.4% (8/234)
dichorionic twins, which was comparable (P=0.70). The incidence of
congenital anomalies was also comparable between mono-zygotic and
dizygotic twins; 1.7% (1/58) and 3.1% (5/162), respectively (P=0.50).
The incidence of congenital anomalies seen in the
present series was comparable with the previously published data. The
association of congenital malformations with zygosity was not evident in
the present series. The limitation of this study was that the data of
twins could not be compared with singletons. A large multicentric Indian
study may throw more light on this subject.
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