title: Population-based study of the incidence of congenital hip dysplasia in preterm infants from the Survey of Neonates in Pomerania (SNiP).
abstract: Some etiological factors involved in developmental dysplasia of the hip (DDH) occur in the last trimester of pregnancy, which could result in a decreased incidence of DDH in preterm infants. The aim of this study was to compare the incidence of DDH between preterm and term infants.
  
  
  
  Ultrasound of the hip joint was performed in 2,534 term infants and 376 preterm infants within the population-based Survey of Neonates in Pomerania (SNiP) study.
  
  
  
  A total of 42 (1.66%) term infants had DDH (Graf type II c, 0.8%; type D, 0.3% left and 0.4% right; type III a, 0.2% left). Eighteen infants had bilateral findings. Hip dysplasia occurred more frequently in female neonates (32/1,182 vs. 10/1,302, p < 0.023; 95% CI 0.012-0.022, χ2test). A familial disposition for DDH was found in 169 (6.7%) term infants and 181 (7.1%) infants in the overall population. In preterm infants, dysplasia of the hip was found in only three late preterm infants with gestational age between 36 and 37 weeks (n = 97) and not in preterm infants <36 weeks gestational age (n = 279). Regression analysis revealed a narrowly significant association between gestational week of birth and DDH (relative risk = 1.17; 95% confidence interval 0.99-1.37; p = 0.065).
  
  
  
  Our study suggests that preterm infants <36 weeks gestational age have a decreased risk of DDH.
authors.affiliation: Departments of Paediatrics and Neonatology & Paediatric Intensive Care Medicine, University of Greifswald, Greifswald, Germany. anja.lange@uni-greifswald.de.|Klinik und Poliklinik für Kinder- und Jugendmedizin, F.-Sauerbruch-Str., 17487, Greifswald, Germany. anja.lange@uni-greifswald.de.
authors.forename: A E
authors.initials: AE
authors.lastname: Lange
authors.affiliation: Department of Trauma Surgery, University of Greifswald, Greifswald, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Lange
authors.affiliation: Institute for Community Medicine, Div. SHIP - Clinical Epidemiological Research, University Medicine Greifswald, Greifswald, Germany.
authors.forename: Till
authors.initials: T
authors.lastname: Ittermann
authors.affiliation: Department of Trauma Surgery, University of Greifswald, Greifswald, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Napp
authors.affiliation: Department of Radiology, University of Greifswald, Greifswald, Germany.
authors.forename: Paul-Christian
authors.initials: PC
authors.lastname: Krueger
authors.affiliation: Departments of Paediatrics and Neonatology & Paediatric Intensive Care Medicine, University of Greifswald, Greifswald, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Bahlmann
authors.affiliation: Department of Orthopaedics and Orthopaedic Surgery, University of Greifswald, Greifswald, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Kasch
authors.affiliation: Departments of Paediatrics and Neonatology & Paediatric Intensive Care Medicine, University of Greifswald, Greifswald, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Heckmann
mesh_terms: D005260:Female; D005858:Germany / Q000453:epidemiology; D005865:Gestational Age; D006306:Health Surveys; D006618:Hip Dislocation, Congenital / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000453:epidemiology*; D008297:Male; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D047929:Term Birth
keywords: Hip dysplasia; Preterm neonate; Screening of neonates; Ultrasound of the hip