Authors
Roshni Radhakrishnana, Ratish Radhakrishnanb
a Department of Obstetrics and gynaecology, Sree Gokulam Medical College & Research Foundation, Kerala, India;
b Department of CVTS, Medical College, Kottayam, Kerala, India
Abstract
Background: Twin pregnancies are a unique but common obstetrical occurrence that has attracted the attention of both the obstetrician and the common man since time immemorial. The number and rate of twin triplet and other higher order multiple births have increased in the United States at an unprecedented pace over the past two decades (Kogan and colleagues, 2000; Martin and Park 1999). Advances in assisted reproduction and an increasing proportion of older mothers have contributed to a steep increase in twin pregnancies. This extraordinary increase in multiple births is a public health concern because these infants are less likely to survive and more likely to suffer lifelong disability due to preterm delivery. Multiple gestations currently accounts for 3% of all pregnancies (ACOG, 1998). Twins account for 94% of all multiple births each year. Despite advances in obstetrics and neonatology, the perinatal mortality rate among twins still remains high, estimated as accounting for approximately 10% of all perinatal mortality. The higher preterm delivery rate in twins, either from spontaneous or induced labour, with its associated problems of prematurity remains the major cause of morbidity and mortality. Other factors which contribute to the higher perinatal mortality include fetal growth retardation, intratwin birth weight discordancy, fetal anomalies and problems specific to monochorionic twin gestations like twin to twin transfusion syndrome. In twins, about 30% are identical or monozygotic and 70% are fraternal or dizygotic. Monozygotic twins result from the fertilization of a single egg followed by early cleavage into two halves, which develop further separately. Monozygotic twins may be dichorionic diamniotic, monochorionic diamniotic, mono-chorionic monoamniotic and even conjoined, depending on the time between fertilization and cleavage. In 30% of monozygotic twins, cleavage occurs by the third day of fertilization resulting in dichorionic diamniotic pregnancy. In 70%, cleavage occurs between the 4th and 8th day, resulting in mono-chorionic diamniotic twins. Rarely, cleavage takes place after the 9th day resulting in monochorionic monoamniotic twins. If division is even later, after the embryonic disk is formed, cleavage is incomplete and conjoined twins are formed.1 Dizygotic twins result from the fertilization of two different eggs, by two spermatozoa and by definition each twin has its own placenta and amniotic sac (dichorionic diamniotic). Monochorionic twin gestations are at increased risk of a variety of pregnancy complications which can be minimized by early antepartum diagnosis and management. This study endeavors to evaluate the influence of chorionicity in twin pregnancies on perinatal outcome.
Materials and Methods: A prospective study was conducted at, Institute of maternal and child health Calicut over a period of one year; 2005 to 2006. The total of, 200 cases of twin pregnancies were followed up from antenatal period, upon their admission to ward and labour room.
Results: Among 200 twin pregnancies, 62% were dichorionic diamniotic twins, 37% were monochorionic diamniotic. Average gestational age of monochorionic twin was 35.7 and that of dichorionic twin was 36.5. Perinatal mortality of monochorionic twin was 180/1000 when compared to 60.5/1000 for dichorionic twin.
Conclusion: Perinatal mortality of monochorionic twin is definitely more when compared to dichorionic twin.