Incidence of respiratory distress syndrome in pre-term twins

Hyaline membrane disease or respiratory distress syndrome (RDS) is a syndrome of respiratory insufficiency due to a deficiency or dysfunction of the pulmonary surfactant. The main risk factors for RDS include decreasing gestational age and birth weight, while twin pregnancy and male sex are also risk factors. The objective of the study is to analyse prospectively the incidence of RDS in premature twins compared with premature singletons. The variables observed were birth order in twins, gestational age, sex, and mortality in twins and singletons. The inclusion criteria were clinical, radiological and laboratory signs of RDS. The setting was the University Department of Obstetrics and Gynaecology, Division of Neonatology, University Clinical Center Tuzla during a four-year period (1999 to 2003). The number of pre-term infants born during the investigation was 1799 (9.5%), with 261 (14.5%) twins. RDS was diagnosed in 301 (16.7%) pre-term infants of whom 221 (14.3%) were singletons and 80 (30.7%) were twins (χ2=42.46;P<0.00001). Second twin, male sex and gestational age 32 to 36 weeks (χ2=85.46;P<0.00001) were the risk factors for RDS development in our examinees. The mortality rate was significantly higher in twins (15%), than in singletons (6.3%) (χ2=5.59;P<0.018) The mortality rate of twins of 28 to 31 weeks of gestation was significantly higher than in singletons of the same gestation (χ2=8.76;P<0.003), while the difference was not statistically significant in infants of 32 to 36 weeks of gestation.