title: Validity of a selection of pregnancy complications in the Medical Birth Registry of Norway.
abstract: BACKGROUND
  The validity of information on pregnancy complications in the Medical Birth Registry of Norway (MBRN) is insufficiently studied. The objective was to examine the validity of information on gestational age, birthweight, medically initiated delivery, and gestational hypertension in the MBRN.
  
  
  METHODS
  We randomly sampled MBRN records among women who participated in the population-based HUNT Study in Nord-Trøndelag county and who gave birth during 1967-2012. We estimated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value of information in the MBRN, using hospital records as the reference standard.
  
  
  RESULTS
  Hospital records were available for 786 out of 797 sampled MBRN records. The PPVs of preterm (<37 weeks of gestation) and early preterm birth (<34 weeks of gestation) were approximately 90%, and the PPVs of low (<2500 g) and high (>4500 g) birthweight were 100%. For medically initiated delivery, the PPV was 28% during 1967-85, but 80% during 1986-2012 and higher among preterm (76%) than among term (51%) births. For gestational hypertension, the PPV was 68%, but 88% of women labeled with gestational hypertension in the MBRN had evidence of gestational hypertension or preeclampsia in hospital records.
  
  
  CONCLUSIONS
  The validity of information on gestational age and birthweight in the MBRN was very good. For medically initiated delivery, the validity was poor before 1985 and satisfactory thereafter. For gestational hypertension, lack of information in hospital records made the evaluation difficult, but our results suggest that most women labeled with gestational hypertension in the MBRN did have a hypertensive disorder of pregnancy.
authors: Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors: Fredrikke N
authors: http://orcid.org/0000-0002-5095-0296
authors: FN
authors: Moth
authors: Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors: Tharani R
authors: http://orcid.org/0000-0003-3839-3690
authors: TR
authors: Sebastian
authors: Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Obstetrics and Gynecology, Levanger Hospital, Nord-Trøndelag Hospital Trust, Levanger, Norway.
authors: Julie
authors: http://orcid.org/0000-0003-1344-9707
authors: J
authors: Horn
authors: Connors Center for Women's Health and Gender Biology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors: Janet
authors: http://orcid.org/0000-0001-5066-8808
authors: J
authors: Rich-Edwards
authors: Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors: Pål R
authors: http://orcid.org/0000-0003-2061-4336
authors: PR
authors: Romundstad
authors: Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.|Department of Endocrinology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
authors: Bjørn O
authors: http://orcid.org/0000-0003-3837-2101
authors: BO
authors: Åsvold
mesh_terms: D000328:Adult; D001724:Birth Weight; D036861:Delivery, Obstetric / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D005865:Gestational Age; D063025:Health Information Management; D006753:Hospital Records / Q000706:statistics & numerical data*; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000175:diagnosis* / Q000453:epidemiology; D007231:Infant, Newborn; D008331:Management Information Systems; D009664:Norway / Q000453:epidemiology; D011247:Pregnancy; D012015:Reference Standards; D012042:Registries / Q000592:standards* / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Birthweight; HUNT; Medical Birth Registry of Norway; gestational age; gestational hypertension; medically initiated delivery; pregnancy; preterm birth; validity