Table 1. Characteristics of study cohort: Overall and by antibiotic exposure status.
| Characteristic: No (%) a | All subjects N = 214 834 |
Antibiotic use during pregnancy | |
|---|---|---|---|
| NO N = 134 084 |
YES N = 80 750 |
||
| Male | 110 107 (51.3) | 68 691 (51.2) | 41 416 (51.3) |
| Urban region | 116 865 (54.4) | 74 887 (55.9) | 41 978 (52.0) |
| Socioeconomic status (SES)b: | |||
| High Middle Low-mid Low |
21 212 (9.9) 77 708 (36.2) 67 059 (31.2) 48 855 (22.7) |
14 912 (11.1) 50 861 (37.9) 40 410 (30.1) 27 901 (20.8) |
6 300 (7.8) 26 847 (33.3) 26 649 (33.0) 20 954 (26.0) |
| Receipt of income assistance c | 37 158 (17.3) | 17 058 (12.7) | 20 100 (24.9) |
| Mothers age at delivery: | |||
| < 30 30–39 > = 40 |
128 229 (59.7) 81 963 (38.2) 4 642 (2.2) |
76 411 (57.0) 54 602 (40.7) 3 071 (2.3) |
51 818 (64.2) 27 361 (33.9) 1 571 (2.0) |
| Breastfeeding initiation d | 172 952 (80.8) | 110 425 (82.7) | 62 527 (77.7) |
| Multiple birth e | 5 383 (2.5) | 3 246 (2.4) | 2 137 (2.7) |
| Caesarian section delivery | 43 782 (20.4) | 26 810 (20.0) | 16 972 (21.0) |
| Birth complications | 21 022 (9.8) | 13 092 (9.8) | 7 930 (9.8) |
| First born child | 80 758 (37.6) | 52 334 (39.0) | 28 424 (35.2) |
| Small for gestational age f | 16 507 (7.7) | 10 445 (7.8) | 6 062 (7.5) |
| Prenatal alcohol/drug use g | 12 959 (12.3) | 7 265 (10.9) | 5 694 (14.7) |
| Prenatal smoking h | 20 844 (19.4) | 10 687 (15.8) | 10 157 (25.7) |
| Childhood medical conditions: | |||
| Infections: | |||
| None Mild-moderate i Severe j Epilepsy Neonatal jaundice Other developmental disabilities Asthma |
67 430 (31.4) 134 794 (62.7) 12 610 (5.9) 1 056 (0.5) 20 517 (9.6) 859 (0.4) 26 641 (12.4) |
48 169 (35.9) 78 881 (58.8) 7 034 (5.3) 589 (0.4) 11 934 (8.9) 489 (0.4) 13 522 (10.1) |
19 261 (23.9) 55 913 (69.2) 5 576 (6.9) 467 (0.6) 8 583 (10.6) 370 (0.5) 13 119 (16.3) |
| Early life antibiotics exposure k | 94 024 (43.8) | 51 524 (38.4) | 42 500 (52.6) |
| Maternal medical conditions: | |||
| Mood and anxiety disorders Schizophrenia Diabetes Infections |
15 885 (7.4) 196 (0.1) 6 085 (2.8) 67 559 (31.5) |
7 493 (5.6) 87 (0.1) 3 268 (2.4) 22 214 (16.6) |
8 392 (10.4) 109 (0.1) 2 817 (3.5) 45 345 (56.2) |
| Prenatal medications use: | |||
| Antidepressants Antipsychotics Anticonvulsants Cardiovascular medications |
5 759 (2.7) 613 (0.3) 1 282 (0.6) 3 370 (1.6) |
2 773 (2.1) 236 (0.2) 552 (0.4) 1 887 (1.4) |
2 986 (3.7) 377 (0.5) 730 (0.9) 1 483 (1.8) |
| Year of birth: | |||
| 1998–2001 2002–2005 2006–2009 2010–2014 |
47 107 (21.9) 48 596 (22.6) 53 052 (24.7) 66 079 (30.8) |
28 817 (21.5) 30 789 (23.0) 33 269 (24.8) 41 209 (30.7) |
18 290 (22.7) 17 807 (22.1) 19 783 (24.5) 24 870 (30.8) |
| Season of birth: | |||
| Winter spring Summer Fall |
49 039 (22.8) 56 517 (26.3) 58 987 (27.5) 50 291 (23.4) |
30 678 (22.9) 34 935 (26.1) 36 831 (27.5) 31 640 (23.6) |
18 361 (22.7) 21 582 (26.7) 22 156 (27.4) 18 651 (23.1) |
a Numbers (percentage). Percentages are calculated based on non-missing data
b SEFI was categorized with cut off points within one standard deviation from the mean into high, middle, low middle and low SES
c Defined as receiving income assistance for at least two months within 1 year before to 18 months after index date
d Missing data for 886 (0.4%) subjects
e Defined as the number of births following a multiple gestation pregnancy
f Defined as having birth weight below the 10th percentile for the gestational age and sex. Missing data for 502 (0.2%) subjects
g Missing data for 109 491 (51.0%) subjects
h Missing data for 107 550 (50.1%) subjects
i Defined as having an infection code in physician claims only
j Defined as having a hospitalization with an infection code
k Defined as filling one or more antibiotic prescription during the first year of life