EP21.01: Incidence of neonatal respiratory distress after 36 weeks of gestation among uncomplicated twin pregnancies according to gestational week of birth

The aim of the study is to reveal the incidence of neonatal respiratory distress (NRD) by gestational week after 36 weeks of gestation (wks) in uncomplicated twin pregnancies. This was a retrospective cohort study of uncomplicated twin pregnancies delivered after 36 wks, who were managed at our centre from April 2008 through December 2017. Cases with fetal abnormality, fetal death, fetal therapy and maternal complications considered an indication for immediate delivery. In principle, expectant management was conducted for cases until 38 wks. Primary outcome was the incidence of NRD, including respiratory distress syndrome, meconium aspiration syndrome, transient tachypnea of the newborn, requiring interventions. The risk factors for NRD were also analysed with a multivariable logistic regression model. The evaluated factors included chorionicity, primiparity, delivery mode, gestational diabetes mellitus, hypertensive disorders, sex and small for gestational age. A total of 606 twin pregnancies were included in the study: 87 at 36wks (Group A), 202 at 37wks (Group B) and 312 at 38wkd (Group C). Fetal death and hypoxic-ischemic encephalopathy was noted in one case each, however, there was no case of neonatal death. The incidence of NRD was 8.0% (14/174 neonates) in Group A, 4.2% (17/404) in B and 2.2% (14/624) in C, respectively. That in Group A was significantly more frequent than Group C. Adjusted odds ratio of Group A for NRD based on Group C was 2.94 (95% Confidence interval, 1.29-6.70). The risk of NRD in uncomplicated twins decreases after 36 wks toward 38 weeks.