TABLE 2

Characteristics of Children Born in Denmark During 2004–2012 and Subgroup-Specific 1-Year Risks of Antibiotic Prescription During Infancy

Total Study Population (N = 561 729)Children With ≥1 Redeemed Antibiotic Prescription During Infancy (n = 220 655, 39.3%)
No. (%a)No.Subgroup-Specific 1-y Risk, % (99% CI)b
Demographics
 Sex of child
  Female273 839 (48.7)97 35735.7 (35.5 to 36.0)
  Male287 890 (51.3)123 29843.0 (42.8 to 43.3)
 Mother’s age at birth (y)
  <2559 371 (10.6)25 84743.8 (43.3 to 44.3)
  25–29.9167 819 (29.9)67 90140.6 (40.3 to 41.0)
  30–34.9213 324 (38.0)83 46939.3 (39.0 to 39.6)
  35–39.9100 886 (18.0)36 77536.6 (36.2 to 37.0)
  ≥4020 329 (3.6)666332.9 (32.1 to 33.8)
 Season of birth
  Winter (December, January, February)132 235 (23.5)52 12039.6 (39.3 to 40.0)
  Spring (March, April, May)139 639 (24.9)62 30544.8 (44.5 to 45.2)
  Summer (June, July, August)149 743 (26.7)58 45739.2 (38.9 to 39.5)
  Autumn (September, October, November)140 112 (24.9)47 77334.3 (33.9 to 34.6)
 Year of birth
  2004–2006192 572 (34.3)79 95741.7 (41.4 to 42.0)
  2007–2009190 580 (33.9)74 38839.2 (38.9 to 39.5)
  2010–2012178 577 (31.8)66 31037.3 (37.0 to 37.6)
 Region of birth
  Capital region190 832 (34.0)73 92639.0 (38.7 to 39.3)
  Zealand region70 089 (12.5)31 95345.7 (45.2 to 46.2)
  Southern region112 140 (20.0)49 42244.2 (43.9 to 44.6)
  Central region137 420 (24.5)45 89133.5 (33.2 to 33.8)
  North region51 248 (9.1)19 46338.1 (37.6 to 38.7)
Pregnancy and birth
 Parity (live births and stillbirths)c
  First pregnancy246 191 (44.5)85 57034.9 (34.7 to 35.2)
  Second203 881 (36.8)88 24843.4 (43.2 to 43.7)
  Third76 312 (13.8)31 78541.8 (41.4 to 42.3)
  Fourth or more27 002 (4.9)11 62743.3 (42.5 to 44.1)
 No. of pregnancy visits to a GP
  087 968 (15.7)32 39637.0 (36.6 to 37.4)
  1–2102 994 (18.3)40 14739.3 (38.9 to 39.7)
  ≥3370 767 (66.0)148 11240.1 (39.9 to 40.3)
 No. of pregnancy visits to midwife
  044 398 (7.9)16 01636.4 (35.8 to 37.0)
  1–221 075 (3.8)783237.9 (37.0 to 38.7)
  ≥3496 256 (88.3)196 80739.8 (39.6 to 40.0)
 No. of pregnancy visits to ob-gyn
  0466 761 (83.1)181 21539.0 (38.8 to 39.2)
  1–257 429 (10.2)23 28740.7 (40.2 to 41.2)
  ≥337 539 (6.7)16 15343.2 (42.6 to 43.9)
 Mother’s pregravid BMI (kg/m2)c
  <18.527 034 (5.1)986636.7 (36.0 to 37.5)
  18.5–24.9326 332 (61.8)122 26037.6 (37.4 to 37.9)
  25–29.9111 711 (21.1)46 20441.5 (41.1 to 41.9)
  ≥3063 267 (12.0)28 17944.7 (44.2 to 45.2)
 Maternal smoking during pregnancyc
  Did not smoke470 150 (85.7)180 42338.6 (38.4 to 38.7)
  Quit during pregnancy14 048 (2.6)573941.0 (40.0 to 42.1)
  Smoking, ≤10 cigarettes/d43 293 (7.9)19 46145.1 (44.5 to 45.7)
  Smoking, >11 cigarettes/d19 749 (3.6)914346.4 (45.5 to 47.4)
  Smoking, amount not reported1542 (0.3)68044.4 (41.2 to 47.7)
 Gestational age at birth (wk)c
  <3736 637 (6.5)13 83338.3 (37.7 to 39.0)
  37–39.9235 805 (42.1)95 14240.5 (40.3 to 40.8)
  ≥40287 561 (51.3)111 04938.8 (38.5 to 39.0)
 Birth weight (g)c
  <250028 767 (5.2)10 10735.8 (35.1 to 36.5)
  2500–3499242 598 (43.5)93 30438.6 (38.4 to 38.9)
  3500–4499269 026 (48.2)108 28140.4 (40.1 to 40.6)
  ≥450017 775 (3.2)765643.2 (42.2 to 44.2)
 Cesarean delivery for this birth123 250 (21.9)49 69340.6 (40.2 to 41.0)
 Cesarean by maternal request15 695 (2.8)695644.4 (43.4 to 45.5)
 Operative vaginal delivery45 183 (8.0)16 36236.4 (35.8 to 37.0)
 Suture to repair birth injury210 068 (37.4)80 30738.4 (38.1 to 38.6)
 Newborn transferred to NICU51 964 (9.3)20 18339.3 (38.8 to 39.9)
 Respiratory aid in NICU23 754 (4.2)895238.6 (37.8 to 39.4)
 Sepsis during first month of life8989 (1.6)341739.1 (37.8 to 40.5)
 Congenital malformation40 733 (7.3)17 52843.6 (42.9 to 44.2)
 Died during first year of life1073 (0.2)6855.9 (38.1 to 75.3)
 Emigrated during first year of life2807 (0.5)32726.0 (22.3 to 30.2)
  • a Column percentages for characteristics in the total study population, which sum to 100%.

  • b Risk estimates are each subgroup’s cumulative incidence for at least 1 redeemed antibiotic prescription during infancy, accounting for censoring at death or emigration; these risk estimates resemble the number of children with ≥1 prescription ÷ the number of children in the subgroup because death and emigration were rare. Risks do not sum to 100%.

  • c Missing data occurred for parity (1.5% of children had missing values), maternal pregravid BMI (5.9%), maternal smoking during pregnancy (2.3%), gestational age at birth (0.3%), and birth weight (0.6%).