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. 2012 Aug 15;2012(8):CD003517. doi: 10.1002/14651858.CD003517.pub2

Comparison 4. Exclusive breastfeeding for 6‐7 months versus 3‐4 months, developed countries, observational studies.

Outcome or subgroup title No. of studies No. of participants Statistical method Effect size
1 Monthly weight gain 3‐8 months (g/mo) 4 4388 Mean Difference (IV, Random, 95% CI) ‐7.95 [‐31.84, 15.93]
2 Monthly weight gain 6‐9 months (g/mo) 2 3432 Mean Difference (IV, Random, 95% CI) 21.11 [‐44.70, 86.91]
3 Monthly weight gain 8‐12 months (g/mo) 3 3450 Mean Difference (IV, Fixed, 95% CI) ‐1.82 [‐16.72, 13.08]
4 Monthly length gain 3‐8 months (cm/mo) 4 4385 Mean Difference (IV, Random, 95% CI) ‐0.03 [‐0.11, 0.06]
5 Monthly length gain 6‐9 months (cm/mo) 2 3430 Mean Difference (IV, Fixed, 95% CI) ‐0.04 [‐0.10, 0.01]
6 Monthly length gain 8‐12 months (cm/mo) 3 3448 Mean Difference (IV, Fixed, 95% CI) 0.09 [0.03, 0.14]
7 Weight‐for‐age z‐score at 6 months 1 3455 Mean Difference (IV, Fixed, 95% CI) ‐0.09 [‐0.16, ‐0.02]
8 Weight‐for‐age z‐score at 9 months 1 3400 Mean Difference (IV, Fixed, 95% CI) ‐0.10 [‐0.18, ‐0.02]
9 Weight‐for‐age z‐score at 12 months 1 3458 Mean Difference (IV, Fixed, 95% CI) ‐0.09 [‐0.17, ‐0.01]
10 Length‐for‐age z‐score at 6 months 1 3454 Mean Difference (IV, Fixed, 95% CI) ‐0.12 [‐0.20, ‐0.04]
11 Length‐for‐age z‐score at 9 months 1 3398 Mean Difference (IV, Fixed, 95% CI) ‐0.14 [‐0.22, ‐0.06]
12 Length‐for‐age z‐score at 12 months 1 3458 Mean Difference (IV, Fixed, 95% CI) ‐0.02 [‐0.10, 0.06]
13 Weight‐for‐length z‐score at 6 months 1 3454 Mean Difference (IV, Fixed, 95% CI) 0.02 [‐0.07, 0.11]
14 Weight‐for‐length z‐score at 9 months 1 3398 Mean Difference (IV, Fixed, 95% CI) 0.03 [‐0.06, 0.12]
15 Weight‐for‐length z‐score at 12 months 1 3458 Mean Difference (IV, Fixed, 95% CI) ‐0.08 [‐0.17, 0.01]
16 Weight‐for‐age z‐score < ‐2 at 6 months 1 3461 Risk Ratio (M‐H, Fixed, 95% CI) 0.92 [0.04, 19.04]
17 Weight‐for‐age z‐score < ‐2 at 9 months 1 3408 Risk Ratio (M‐H, Fixed, 95% CI) 1.52 [0.16, 14.62]
18 Weight‐for‐age z‐score < ‐2 at 12 months 1 3466 Risk Ratio (M‐H, Fixed, 95% CI) 1.15 [0.13, 10.31]
19 Length‐for‐age z‐score < ‐2 at 6 months 1 3460 Risk Ratio (M‐H, Fixed, 95% CI) 1.53 [0.84, 2.78]
20 Length‐for‐age z‐score < ‐2 at 9 months 1 3406 Risk Ratio (M‐H, Fixed, 95% CI) 1.46 [0.80, 2.64]
21 Length‐for‐age z‐score < ‐2 at 12 months 1 3466 Risk Ratio (M‐H, Fixed, 95% CI) 0.66 [0.23, 1.87]
22 Weight‐for‐length z‐score < ‐2 at 6 months 1 3460 Risk Ratio (M‐H, Fixed, 95% CI) 0.31 [0.02, 5.34]
23 Weight‐for‐length z‐score < ‐2 at 9 months 1 3406 Risk Ratio (M‐H, Fixed, 95% CI) 1.14 [0.24, 5.37]
24 Weight‐for‐length z‐score < ‐2 at 12 months 1 3466 Risk Ratio (M‐H, Fixed, 95% CI) 1.15 [0.13, 10.31]
25 Head circumference at 6 months (cm) 1 3440 Mean Difference (IV, Fixed, 95% CI) ‐0.10 [‐0.23, 0.03]
26 Head circumference at 9 months (cm) 1 3389 Mean Difference (IV, Fixed, 95% CI) 0.07 [‐0.06, 0.20]
27 Head circumference at 12 months (cm) 1 3450 Mean Difference (IV, Fixed, 95% CI) 0.19 [0.06, 0.32]
28 Sleeping time at 9 months (min/day) 1 50 Mean Difference (IV, Fixed, 95% CI) 1.0 [‐36.65, 38.65]
29 Total essential amino acid concentration (umol/L) at 6 months 1 44 Mean Difference (IV, Fixed, 95% CI) 22.0 [‐59.60, 103.60]
30 Total amino acid concentration (umol/L) at 6 months 1 44 Mean Difference (IV, Fixed, 95% CI) 73.0 [‐118.22, 264.22]
31 Atopic eczema in first 12 months 2 3618 Risk Ratio (M‐H, Random, 95% CI) 0.65 [0.27, 1.59]
32 Food allergy at 1 year (by history) 1 135 Risk Ratio (M‐H, Fixed, 95% CI) 0.19 [0.08, 0.48]
33 Food allergy at 1 year (by double challenge) 1 135 Risk Ratio (M‐H, Fixed, 95% CI) 0.77 [0.25, 2.41]
34 Two or more episodes of wheezing in first 12 months 2 3993 Risk Ratio (M‐H, Fixed, 95% CI) 0.79 [0.49, 1.28]
35 Hemoglobin concentration (g/L) at 12 months 1 30 Mean Difference (IV, Fixed, 95% CI) 8.0 [4.03, 11.97]
36 Hemoglobin concentration < 110 g/L at 12 months 1 30 Risk Ratio (M‐H, Fixed, 95% CI) 0.12 [0.01, 1.80]
37 Serum ferritin concentration (mcg/L) at 12 months 1 30 Mean Difference (IV, Fixed, 95% CI) 4.70 [‐6.30, 15.70]
38 Serum ferritin concentration < 10 mcg/L at 12 months 1 30 Risk Ratio (M‐H, Fixed, 95% CI) 0.42 [0.12, 1.54]
39 One or more episodes of gastrointestinal infection in first 12 months 1 3483 Risk Ratio (M‐H, Fixed, 95% CI) 0.67 [0.46, 0.97]
40 Hospitalization for gastrointestinal infection in first 12 months 1 3483 Risk Ratio (M‐H, Fixed, 95% CI) 0.79 [0.42, 1.49]
41 One or more episodes of upper respiratory tract infection in first 12 months 1 510 Risk Ratio (M‐H, Fixed, 95% CI) 1.07 [0.96, 1.20]
42 Two or more episodes of upper respiratory tract infection in first 12 months 2 3993 Risk Ratio (M‐H, Fixed, 95% CI) 0.91 [0.82, 1.02]
43 Four or more episodes of upper respiratory tract infection in first 12 months 1 510 Risk Ratio (M‐H, Fixed, 95% CI) 0.82 [0.52, 1.29]
44 One or more episodes of lower respiratory tract infection in first 12 months 1 510 Risk Ratio (M‐H, Fixed, 95% CI) 1.07 [0.86, 1.33]
45 Two or more episodes of respiratory tract infection (upper or lower) in first 12 months 1 3483 Risk Ratio (M‐H, Fixed, 95% CI) 0.90 [0.79, 1.03]
46 Hospitalization for respiratory tract infection in first 12 months 2 3993 Risk Ratio (M‐H, Fixed, 95% CI) 0.75 [0.60, 0.94]
47 Number of episodes of otitis media in first 12 months 1 279 Mean Difference (IV, Fixed, 95% CI) ‐0.04 [‐0.49, 0.41]
48 One or more episodes of otitis media in first 12 months 2 3762 Risk Ratio (M‐H, Fixed, 95% CI) 1.28 [1.04, 1.57]
49 Frequent otitis media in first 12 months 1 279 Risk Ratio (M‐H, Fixed, 95% CI) 0.81 [0.43, 1.52]
50 Death in first 12 months 1 3483 Risk Ratio (M‐H, Fixed, 95% CI) 2.30 [0.21, 25.37]
51 Any dental caries (decayed, missing, or filled teeth) at 6 years 1 2948 Risk Ratio (M‐H, Fixed, 95% CI) 0.98 [0.94, 1.03]
52 Any incisor caries (decayed, missing, or filled teeth) at 6 years 1 2948 Odds Ratio (M‐H, Fixed, 95% CI) 0.91 [0.72, 1.16]
53 Height at 6.5 years 1 2951 Mean Difference (IV, Fixed, 95% CI) 0.10 [‐0.40, 0.60]
54 Leg length at 6.5 years 1 2951 Mean Difference (IV, Fixed, 95% CI) 0.20 [‐0.14, 0.54]
55 Head circumference at 6.5 years 1 2951 Mean Difference (IV, Fixed, 95% CI) 0.10 [‐0.04, 0.24]
56 BMI at 6.5 years 1 2951 Mean Difference (IV, Fixed, 95% CI) 0.20 [0.02, 0.38]
57 Triceps skinfold thickness at 6.5 years 1 2951 Mean Difference (IV, Fixed, 95% CI) 0.90 [0.51, 1.29]
58 Subscapular skinfold thickness 1 2951 Mean Difference (IV, Fixed, 95% CI) 0.5 [0.25, 0.75]
59 Waist circumference at 6.5 years 1 2951 Mean Difference (IV, Fixed, 95% CI) 0.0 [‐0.42, 0.42]
60 Hip circumference at 6.5 years 1 2951 Mean Difference (IV, Fixed, 95% CI) 0.5 [0.05, 0.95]
61 Systolic blood pressure at 6.5 years 1 2951 Mean Difference (IV, Fixed, 95% CI) 1.30 [0.39, 2.21]
62 Diastolic blood pressure at 6.5 years (mm Hg) 1 2951 Mean Difference (IV, Fixed, 95% CI) 1.0 [0.29, 1.71]
63 Atopic eczema at 5‐7 years 2 3584 Risk Ratio (M‐H, Fixed, 95% CI) 0.86 [0.47, 1.58]
64 Hay fever at 5‐7 years 2 3584 Risk Ratio (M‐H, Random, 95% CI) 0.80 [0.39, 1.65]
65 Asthma at 5‐7 years 3 4023 Risk Ratio (M‐H, Fixed, 95% CI) 1.02 [0.72, 1.44]
66 Food allergy at 5 years 1 113 Risk Ratio (M‐H, Fixed, 95% CI) 0.61 [0.12, 3.19]
67 Allergy to animal dander at 5 years 1 113 Risk Ratio (M‐H, Fixed, 95% CI) 0.81 [0.24, 2.72]
68 Positive skin‐prick test to house dust mite at 6.5 years 1 2320 Odds Ratio (M‐H, Fixed, 95% CI) 0.86 [0.62, 1.20]
69 Positive skin‐prick test to cat dander at 6.5 years 1 2320 Odds Ratio (M‐H, Fixed, 95% CI) 0.86 [0.60, 1.24]
70 Positive skin‐prick test to birch pollen at 6.5 years 1 2320 Odds Ratio (M‐H, Fixed, 95% CI) 0.80 [0.55, 1.18]
71 Positive skin‐prick test to mixed northern grasses at 6.5 years 1 2320 Odds Ratio (M‐H, Fixed, 95% CI) 0.71 [0.50, 1.01]
72 Positive skin‐prick test to Alternaria at 6.5 years 1 2320 Odds Ratio (M‐H, Fixed, 95% CI) 0.74 [0.47, 1.17]
73 Any positive skin‐prick test at 6‐7 years 2 2651 Risk Ratio (M‐H, Fixed, 95% CI) 0.95 [0.81, 1.11]
74 Wechsler cognitive ability test at 6.5 years: vocabulary 1 2944 Mean Difference (IV, Fixed, 95% CI) 0.5 [‐0.57, 1.57]
75 Wechsler cognitive ability test at 6.5 years: similarities 1 2944 Mean Difference (IV, Fixed, 95% CI) 0.30 [‐0.56, 1.16]
76 Wechsler cognitive ability test at 6.5 years: matrices 1 2944 Mean Difference (IV, Fixed, 95% CI) ‐0.20 [‐1.07, 0.67]
77 Wechsler cognitive ability test at 6.5 years: block designs 1 2944 Mean Difference (IV, Fixed, 95% CI) 1.30 [0.40, 2.20]
78 Wechsler cognitive ability test at 6.5 years: verbal IQ 1 2944 Mean Difference (IV, Fixed, 95% CI) 0.5 [‐0.95, 1.95]
79 Wechsler cognitive ability test at 6.5 years: performance IQ 1 2944 Mean Difference (IV, Fixed, 95% CI) 0.80 [‐0.55, 2.15]
80 Wechsler cognitive ability test at 6.5 years: full‐scale IQ 1 2944 Mean Difference (IV, Fixed, 95% CI) 0.80 [‐0.58, 2.18]
81 Teacher's academic rating at 6.5 years: reading 1 2196 Mean Difference (IV, Fixed, 95% CI) ‐0.10 [‐0.19, ‐0.01]
82 Teacher's academic rating at 6.5 years: writing 1 2196 Mean Difference (IV, Fixed, 95% CI) ‐0.12 [‐0.20, ‐0.04]
83 Teacher's academic rating at 6.5 years: mathematics 1 2196 Mean Difference (IV, Fixed, 95% CI) ‐0.04 [‐0.12, 0.04]
84 Teacher's academic rating at 6.5 years: other subjects 1 2196 Mean Difference (IV, Fixed, 95% CI) ‐0.10 [‐0.17, ‐0.03]
85 Parent's behavior rating at 6.5 years: total difficulties 1 2941 Mean Difference (IV, Fixed, 95% CI) 0.30 [‐0.16, 0.76]
86 Parent's behavior rating at 6.5 years: emotional symptoms 1 2941 Mean Difference (IV, Fixed, 95% CI) 0.10 [‐0.09, 0.29]
87 Parent's behavior rating at 6.5 years: conduct problems 1 2941 Mean Difference (IV, Fixed, 95% CI) 0.0 [‐0.13, 0.13]
88 Parent's behavior rating at 6.5 years: hyperactivity/inattention 1 2941 Mean Difference (IV, Fixed, 95% CI) 0.20 [‐0.01, 0.41]
89 Parent's behavior rating at 6.5 years: peer problems 1 2941 Mean Difference (IV, Fixed, 95% CI) 0.10 [‐0.05, 0.25]
90 Parent's behavior rating at 6.5 years: prosocial behavior 1 2941 Mean Difference (IV, Fixed, 95% CI) 0.10 [‐0.05, 0.25]
91 Teacher's behavior rating at 6.5 years: total difficulties 1 2525 Mean Difference (IV, Fixed, 95% CI) 0.10 [‐0.46, 0.66]
92 Teacher's behavior rating at 6.5 years: emotional symptoms 1 2525 Mean Difference (IV, Fixed, 95% CI) 0.0 [‐0.18, 0.18]
93 Teacher's behavior rating at 6.5 years: conduct problems 1 2525 Mean Difference (IV, Fixed, 95% CI) 0.0 [‐0.17, 0.17]
94 Teacher's behavior rating at 6.5 years: hyperactivity/inattention 1 2525 Mean Difference (IV, Fixed, 95% CI) ‐0.10 [‐0.37, 0.17]
95 Teacher's behavior rating at 6.5 years: peer problems 1 2525 Mean Difference (IV, Fixed, 95% CI) 0.10 [‐0.08, 0.28]
96 Teacher's behavior rating at 6.5 years: prosocial behavior 1 2525 Mean Difference (IV, Fixed, 95% CI) ‐0.10 [‐0.33, 0.13]