title: Time to spontaneous ductus arteriosus closure in full-term neonates.
abstract: The mean closure time of the ductus arteriosus (DA) in full-term neonates is presumed to be 1-2 days after birth; however, whether this rate is accurate throughout the neonatal period is still unclear. In addition, the clinical determinants that influence DA closure remain unknown.
  
  
  
  Echocardiography was performed 1826 times (897 in boys, 929 in girls) in 1442 participants (732 boys, 710 girls). An iE33 colour Doppler echocardiograph supplied by Philips Electronics was employed to examine DA flow. Data regarding sex, birth date, examination date, method of delivery, mother's age, past deliveries, neonatal body weight and body height were also collected. The Statistical Analysis System makes statistical clarification of these queries possible. We examined the persistence of DA in full-term neonates and appropriate for gestational age (AGA) neonates in the early neonatal period using colour Doppler echocardiography, and a subsequent analysis with SAS.
  
  
  
  After performing multivariable analyses, the median DA persistency times were 27.42 and 45.10 h after birth in boys and girls, respectively. A statistically significant sex difference was observed (p<0.0001). Additionally, significant time differences were observed between vaginal and scheduled caesarean deliveries, at 26.97 and 28.93 h, respectively (p=0.0245). No significant differences were observed in the other variables.
  
  
  
  Spontaneous DA closure time curves were clarified for the first time throughout the early neonatal period in full-term and AGA neonates. It was revealed that both sex and delivery method play important roles in time to DA closure.
authors.affiliation: Department of Neonatology , Gifu Prefectural General Medical Center , Gifu , Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nagasawa
authors.affiliation: Department of Industrial Management & Engineering , Tokyo University of Science , Tokyo , Japan.
authors.forename: Chikuma
authors.initials: C
authors.lastname: Hamada
authors.affiliation: Department of Industrial Management & Engineering , Tokyo University of Science , Tokyo , Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Wakabayashi
authors.affiliation: Department of Industrial Management & Engineering , Tokyo University of Science , Tokyo , Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nakagawa
authors.affiliation: Department of Industrial Management & Engineering , Tokyo University of Science , Tokyo , Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nomura
authors.affiliation: Department of Neonatology , Gifu Prefectural General Medical Center , Gifu , Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kohno
keywords: Statistics and study design