Table 2 Risk of infection and risk ratios for infection according to the duration of exclusive breastfeeding

From: Exclusive breastfeeding duration and infant infection

  Never BF EBF <2 months EBF 2–4 months EBF 4–6 months EBF 6+ months
  Group 1 N=5382 Group 2 N=5645 Group 3 N=2335 BF <6 months, had formula and/or solids before 6 months BF 6+ months, had formula and solids before 6 months BF 6+ months, had solids but no formula before 6 months Group 8 (post-2001 WHO policy) N=190
     Group 4 N=533 Group 5 N=556 Group 7 (pre-2001 WHO policy) N=1122  
Any ear infections a
 No (%) 500 (9.6) 539 (10.3) 240 (11.4) 50 (10.8) 62 (11.1) 96 (10.0) 14 (8.4)
 Crude RR (95% CI) 0.96 (0.74, 1.24) 1.03 (0.80, 1.34) 1.11 (0.85, 1.44) 1.09 (0.74, 1.60) 1.11 (0.75, 1.65) Reference 0.84 (0.45, 1.58)
 Adjusted RR (95% CI) 0.99 (0.76, 1.30) 1.05 (0.82, 1.36) 1.07 (0.83, 1.40) 1.06 (0.72, 1.56) 1.07 (0.72, 1.58) Reference 0.91 (0.49, 1.69)
Any chest infections b
 No (%) 1589 (30.6) 1529 (29.2) 662 (29.5) 134 (27.7) 141 (25.8) 240 (22.9) 30 (18.4)
 Crude RR (95% CI) 1.34 (1.13, 1.57) 1.27 (1.10, 1.47) 1.28 (1.09, 1.51) 1.21 (0.98, 1.48) 1.12 (0.95, 1.34) Reference 0.80 (0.55, 1.17)
 Adjusted RR (95% CI) 1.28 (1.09, 1.51) 1.24 (1.08, 1.43) 1.24 (1.05, 1.45) 1.19 (0.97, 1.46) 1.11 (0.93, 1.32) Reference 0.84 (0.57 1.23)
Any persistent/severe diarrhoea c
 No (%) 413 (8.8) 511 (10.4) 197 (8.9) 47 (10.5) 42 (8.6) 56 (5.9) 9 (5.2)
 Crude RR (95% CI) 1.50 (1.12, 2.02) 1.77 (1.33, 2.34) 1.52 (1.13, 2.04) 1.78 (1.19, 2.68) 1.47 (0.97, 2.24) Reference 0.89 (0.41, 1.94)
 Adjusted RR (95% CI) 1.54 (1.13, 2.09) 1.66 (1.25, 2.20) 1.42 (1.06, 1.92) 1.66 (1.11, 2.47) 1.42 (0.94, 2.16) Reference 0.97 (0.45, 2.09)
Hospitalisation for LRTI d
 No (%) 274 (4.8) 201 (3.8) 72 (2.8) 7 (1.4) 13 (1.7) 26 (1.9) 2 (0.7)
 Crude RR (95% CI) 2.53 (1.57, 4.08) 1.99 (1.21, 3.27) 1.47 (0.84, 2.57) 0.74 (0.30, 1.86) 0.91 (0.41, 2.02) Reference 0.36 (0.07, 1.87)
 Adjusted RR (95% CI) 1.62 (0.98, 2.69) 1.70 (1.02, 2.84) 1.33 (0.76, 2.33) 0.71 (0.28, 1.78) 0.96 (0.43, 2.11) Reference 0.36 (0.07, 1.86)
Hospitalisation for diarrhoea e
 No (%) 97 (1.8) 90 (1.7) 21 (0.9) 5 (0.6) 3 (0.5) 2 (0.1) 2 (0.5)
  1. Abbreviations: BF, breastfed; CI, confidence interval; EBF, exclusively breastfed; LRTI, lower respiratory tract infection.
  2. All adjusted risk ratios are adjusted for infant’s sex and age at recruitment.
  3. aRisk ratios for ear infection are also adjusted for infant’s ethnicity, gestational age, mother’s education, household income, age started childcare and other sibling (n=15,734).
  4. bRisk ratios for chest infection are also adjusted for infant’s ethnicity, gestational age, mother’s education, family history of asthma, age started childcare and other siblings (n=15 731).
  5. cRisk ratios for diarrhoea are also adjusted for mother’s education, household income, crowding and other siblings (n=15 781).
  6. dRisk ratios for hospitalisation for LRTI are also adjusted for infant’s ethnicity, mother’s age, gestational age, mother’s education and other siblings (n=15 750).
  7. eRisk ratios for hospitalisation for diarrhoea were not estimated due to small numbers in the reference group.