Article Text

Comparison of birth weight between school health records and medical birth records in Denmark: determinants of discrepancies
  1. Camilla Bjørn Jensen1,2,
  2. Michael Gamborg1,
  3. Berit Heitmann3,4,5,
  4. Thorkild I A Sørensen1,6,7,
  5. Jennifer L Baker1,6
  1. 1Institute of Preventive Medicine, Bispebjerg and Frederiksberg Hospital, The Capital Region, Copenhagen, Denmark
  2. 2Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
  3. 3Research Unit of Dietary Studies, Parker Institute, Bispebjerg and Frederiksberg Hospital, The Capital Region, Copenhagen, Denmark
  4. 4The Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders, University of Sydney, Sydney, New South Wales, Australia
  5. 5National Institute of Public Health, University of Southern Denmark, Denmark
  6. 6Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Denmark
  7. 7MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
  1. Correspondence to Camilla Bjørn Jensen; Camilla.bjoern.jensen{at}


Objective To compare reported birth weight (BW) information in school health records with BW from medical birth records, and to investigate if maternal and offspring characteristics were associated with any discrepancies.

Design Register-based cohort study.

Setting Denmark, 1973–1991.

Participants The study was based on BW recorded in the Copenhagen School Health Records Register (CSHRR) and in The Medical Birth Register (MBR). The registers were linked via the Danish personal identification number.

Primary and secondary outcome measures Statistical comparisons of BW in the registers were performed using t tests, Pearson's correlation coefficients, Bland-Altman plots and κ coefficients. Odds of BW discrepancies >100 g were examined by logistic regressions.

Results The study population included 47 534 children. From 1973 to 1979 when BW was grouped in 500 g intervals in the MBR, mean BW differed significantly between the registers. During 1979–1991 when BW was recorded in 10 and 1 g intervals, mean BW did not significantly differ between the two registers. BW from both registers was highly correlated (0.93–0.97). Odds of a BW discrepancy significantly increased with parity, the child's age at recall and by marital status (children of married women had the highest odds).

Conclusions Overall, BW information in school health records agreed very well with BW from medical birth records, suggesting that reports of BWs in school health records in Copenhagen, Denmark generally are valid.


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