Poor agreement between self-reported birth weight and birth weight from original records in adult women

Data from an ongoing prospective population study of women in Goteborg, Swe den, were used to assess agreement between self-reported birth weight and b irth weight obtained from original delivery records of women aged 44-60 yea rs. Of the eligible population with traced delivery records (n = 693), only 28% (n = 192) could report their own birth weight. Spearman correlation be tween self-reported birth weight and birth weight from original records was r = 0.76. However, a difference plot, with limits of agreement at -1,028 t o 1,038 g (95% confidence limits: lower limit, -1,157 to -901 g, upper limi t, 910 to 1,166 g) revealed poor agreement between methods. Of the self-rep orted birth weights, 53% were in error by 250 g or more, and 31% were posit ively or negatively discordant by 500 g or more. Application in an analysis of cardiovascular risk factors in adulthood found conflicting results betw een self-reported and recorded birth weights. Low reporting rate, poor repo rting accuracy, and misleading findings in application led to the conclusio n that self-reported birth weights from middle-aged women would not be a sa tisfactory replacement for birth weights from original records.