Perinatal outcome of twins in relation to chorionicity.

Twin gestation, a high-risk pregnancy is responsible for 10% of all perinatal mortalities. The high perinatal mortality of twins has been repeatedly stressed over the years. Studies have also revealed difference in the perinatal mortality rates in relation to chorionicity. Thus, a prospective study of 100 twin pregnancies was carried out at our institute to assess the morbidity and mortality of twins in relation to chorionicity and to analyse the factors responsible for the greater loss. The perinatal mortality rate of monochorionic twins was 17.64% and that of dichorionic twins was 8. 88%, which is statistically significant. Birth weight was found to be the most important factor correlating with mortality rates. The higher perinatal mortality of monochorionic twins was largely due to low birth weights (29.3% of monochorionic twins weighed less than 1500 gm as compared to 12.6% of dichorionic twins). Avoidable deaths were comparable in the two twin groups but dichorionic twins showed greater percentage of fresh stillbirths (40%) whereas in monochorionic twins, 50% were macerated stillbirths. Prematurity was another common factor responsible for greater perinatal mortality in monochorionic twins. Monochorionic twins showed increased incidence of discordant growth (34.8%) as compared to that of dichorionic twins (14.08%). The type of placentation did influence the perinatal outcome of twins making its antenatal diagnosis important.