Table 1.
Descriptive overview of infants in the study.
| New Hampshire Birth Cohort Study (NHBCS) Antibiotic Exposure Cohort (n = 183) | NHBCS Antibiotic Frequency Cohort (n = 99) | DIABIMMUNE Study (n = 33) | |
|---|---|---|---|
| Antibiotic classification derivation | Combination of medical record review and parental recall | Medical record review | Parental recall |
| Mean (SD) sample age in days | Baseline: 46 (15) | Baseline: 45 (16) | Baseline: 64 (15) |
| 1 year: 371 (29) | 1 year: 376 (29) | 1 year: 366.6 (15) | |
| Female | 70 (38.3%) | 40 (40.4%) | 14 (42.4%) |
| Vaginal delivery | 131 (71.6%) | 67 (67.7%) | 29 (87.9%) |
| Mean (SD) days breastfeeding by sample collection | Baselinea: 43.0 (17.7) | Baselinea: 41.8 (18.9) | Baseline: 64 (15) |
| 1 year: 247 (133) | 1 year: 238 (140) | 1 year: 281 (99) | |
| Attend day care by 1 year | Yes: 76 (41.5%) | Yes: 38 (38.4%) | N/A |
| No: 91 (49.7%) | No: 45 (45.5%) | ||
| Missing: 16 (8.7%) | Missing: 16 (16.2%) | ||
| Full-term (at least 37 weeks’ gestation) | 171 (93.4%) | 91 (92.0%) | 31 (94.0%) |
| Parity | 0: 89 (48.6%) | 0: 44 (44.4%) | N/A |
| 1: 62 (33.9%) | 1: 41 (41.4%) | ||
| 2+: 26 (14.2%) | 2+: 13 (13.1%) | ||
| Missing: 6 (3.3%) | Missing: 1 (1.0%) | ||
| Maternal education level | High school or equivalent: 16 (8.7%) | High school or equivalent: 9 (9.1%) | N/A |
| Junior college, technical school, or some college: 26 (14.2%) | Junior college, technical school, or some college: 15 (15.2%) | ||
| College: 67 (36.6%) | College: 38 (38.4%) | ||
| Post-graduate: 71 (38.8%) | Post-graduate: 36 (36.4%) | ||
| Missing: 3 (1.6%) | Missing: 1 (1.0%) | ||
| Antibiotic exposure immediately following birth | 6 (3.3%) | 3 (3.0%) | 1 (3.0%) |
| Missing: 3 (1.6%) | |||
| Number of antibiotic prescriptions between 6 weeks and 1 year | N/A | For otitis media: 42 | For otitis media: 36 |
| Not otitis mediab: 5 | Not otitis media: 0 | ||
| Children with antibiotic exposure between 6 weeks and 1 year | For otitis media: 58 (31.7%) | For otitis media: 27 (27.3%) | For otitis media or any condition: 13 (39.4%) |
| For any conditionc: 63 (34.4%) | For any condition: 29 (29.3%) | ||
| Number of antibiotics for otitis media given to child | N/A | 0: 72 | 0: 20 |
| 1: 15 | 1: 3 | ||
| 2+: 12 | 2+: 10 | ||
| Number of antibiotics for any reason given to child between baseline and 1-year time point | N/A | 0: 70 | 0: 20 |
| 1: 15 | 1: 3 | ||
| 2+: 14 | 2+: 10 | ||
| Number of prescriptions by antibiotic type between baseline and 1-year time point | N/A | Amoxicillin-type: 37 | Amoxicillin-type: 20 |
| Cephalosporin-type: 8 | Cephalosporin-type: 7 | ||
| Azithromycin: 2 | Azithromycin: 5 | ||
| Trimetoprime and sulfadiazine: 3 | |||
| Unknown: 1 |
aOne infant included in both NHBCS sub-cohorts did not have available breastfeeding information at baseline.
bOther reasons included: upper respiratory infection (2), pneumonia (1), bronchitis (1), and reaction to pneumococcal vaccine (1).
cOther reasons included: upper respiratory infection (2), eye infection (1), pneumonia (1), and strep throat (1).