Table 1

Descriptive characteristics of the study cohort of all Danish singleton children born 1995–2003 and followed from 1995 to 2004 (N=577 627)

AllAntibiotic users (N=489 946)
NPerson-years of follow-upNPerson-years of follow-upPrevalence (%)
Calendar year*
 1995681123439910731230715.8
 1996133029100155511503092438.5
 19971978221654051045217693052.8
 199826091522879715978613165761.2
 199932396129184921024818446964.9
 200038750335471426449223903268.3
 200144904241727632221129496071.8
 200250888547757338183135274275.0
 200356894953686143654040940576.7
 200456656556608848502846372785.6
Age*
 05776275744492542309128344.0
 157304954133840672133261171.0
 250961247874840809036799580.1
 344739541638338142734640685.3
 438443535256133992130742888.4
 532023828903628982525936490.5
 625702122581523635020652992.0
 719421416274918069315087893.0
 8130062983071220269196393.8
 96634133732624503169694.1
Sex
 Girls2966621543524233984103217978.9
 Boys2809651629594255962115397391.1
Mother's origin
 Born in Denmark4978332768868424889191609985.3
 Born abroad797944042496505727005381.5
Mother's age at birth
 ≤19100855854888194212387.4
 20–24811714726137120533933487.7
 25–29213051118674918249282771985.7
 30–34192120103863916135770770384.0
 35–39707943637165780223611481.6
 ≥40104065285282713315979.5
Mother's educational level
 Primary school13915680462312202757997487.7
 Secondary school797794315426667028795883.6
 Short tertiary education236160130323720168690819985.4
 Medium or long tertiary education1225326337159956341002181.3
Socioeconomic status
 Self-employed/co-working spouse494552793744172118947284.4
 Employment with high level qualifications803874198176555227207381.5
 Employment with medium level qualifications661313538625550823883083.9
 Employment with basic or no qualifications2742761553996237358109955586.5
 Employment with unknown qualifications358841834202986612447083.2
 Outside labour market714943826495994126175183.8
Birth order
 1249227136654321141293021384.8
 2215251118770218371383146385.3
 3831174572476997231498084.2
 ≥4300321616252484910949682.7
Birth weight (g)
 ≤249920494107172170897645683.4
 2500–2999581553199174976022251585.6
 3000–349917740997800915056467406784.9
 3500–3999205859113461117421177722584.6
 ≥40001157106334099832243588885.0
Gestational age (weeks)
 ≤3376923731261872681380.4
 34–3620052107374172567625886.1
 37–39215782115926018348880199285.0
 40–412847611589549240985108896084.6
 ≥42493402796234203019212985.2
Place of birth
 Copenhagen774434078416429227352383.0
 Copenhagen suburbs844944653687362233446987.1
 Population ≥100 000735614016405985026174781.4
 Population 10 000–99 99915657886979313390960374585.5
 Population ≤9999185551102847515827371266785.3
  • * Since each child can contribute follow-up in different age and calendar periods, the column numbers for age and calendar period sum to more than the total number of children.