Table 1 Participant characteristics
| Â | Study of NP microbiota over time | Study of association between NP microbiota and exposures |
|---|---|---|
N = 103 | N = 99 | |
Participant characteristics | n (%) | n (%) |
Perinatal factors | ||
 Birth season | ||
  Autumn (April–May) | 10 (10) | 10 (10) |
  Winter (June–August) | 29 (28) | 29 (29) |
  Spring (September–November) | 26 (25) | 23 (23) |
  Summer (December–March) | 38 (37) | 37 (38) |
 Sex | ||
  Female | 61 (59) | 59 (60) |
 Mode of delivery | ||
  Cesarean-section delivery | 21 (20) | 21 (21) |
 Gestational age | ||
  Preterm (< 37 weeks) | 14 (13) | 13 (13) |
  37 to 40 weeks | 76 (74) | 74 (75) |
   > 40 weeks | 13 (13) | 12 (12) |
 WAZ at birth | ||
  Low WAZ (< -1 SD below the mean WAZ score) | 29 (28) | 29 (29) |
  Medium WAZ (-1 to 1 SD of the mean WAZ score) | 65 (63) | 61 (62) |
  High WAZ (> 1 SD above the mean WAZ score) | 10 (9) | 9 (9) |
 Duration of exclusive breastfeeding | ||
   < 1 month or none | 32 (31) | 30 (31) |
  Until 1 month | 29 (28) | 28 (28) |
  Until 2–3 months | 21 (20) | 21 (21) |
  Until 4–6 months | 21 (20) | 20 (20) |
Environmental exposures | ||
 Maternal tobacco use (self-reported) | ||
  Yes | 15 (15) | 15 (15) |
 Pets in the home during the 1st 3 months of life | ||
  Yes | 23 (22) | 23 (23) |
 Older siblings | ||
  Yes | 70 (68) | 66 (67) |
 First day-care attendance (prior to specimen collection) | ||
  At 0–6 months of age (yes) | 7 (7) | 6 (6) |
  At 7–12 months of age (yes) | 12 (12) | 12 (12) |
Sociodemographic variables | ||
 Total household income | ||
   < 1000 ZAR (< 64 USD) per month | 48 (47) | 46 (47) |
  1000–5000 ZAR (64–320 USD) per month | 42 (41) | 41 (41) |
   > 5000 ZAR (> 320 USD) per month | 13 (12) | 12 (12) |
 Maternal educational attainment | ||
  Completed primary level education | 71 (69) | 68 (69) |
  Completed secondary level education | 32 (31) | 31 (31) |
Infant exposures | ||
 Immunization cover | ||
  Bacille Calmette-Guérin at birth | 103 (100) | 99 (100) |
  Diphtheria, tetanus, and acellular pertussis: 3 doses | 103 (100) | 99 (100) |
  Pneumococcal conjugate vaccine: 3 doses | 102 (99) | 98 (99) |
  Measles, mumps, rubella at 9 months | 102 (99) | 98 (99) |
  Oral polio vaccine: 3 doses | 103 (100) | 99 (100) |
 Antibiotic administration | ||
  At 0–6 months of age (yes) | 15 (15) | 15 (15) |
  At 7–12 months of age (yes) | 29 (28) | 29 (29) |
 INH prophylaxis | ||
  At 6–12 months of age (yes) | 9 (9) | 9 (9) |
 WAZ at 12 months of age | ||
  Low WAZ (≤ 1 SD below the mean WAZ score) | 17 (17) | 17 (17) |
  Medium WAZ (− 1 to 1 SD of the mean WAZ score) | 68 (66) | 66 (67) |
  High WAZ (> 1 SD above the mean WAZ score) | 18 (17) | 16 (16) |
 HAZ at 12 months of age | ||
  Low HAZ (≤ 1 SD below the mean HAZ score) | 31 (30) | 31 (31) |
  Medium HAZ (− 1 to 1 SD of the mean HAZ score) | 64 (62) | 61 (62) |
  High HAZ (> 1 SD above the mean HAZ score) | 8 (8) | 7 (7) |
 HIV-exposure | ||
  HIV-exposed, uninfected | 26 (25) | 23 (23) |