Setting | Direction of findings | Number of studies (%) | Quality grading (%) |
---|---|---|---|
Developing countries (n=13) | No association between IQ and BF | 6 (46) | A—0 (0) |
B—2 (33.3) | |||
C—4 (66.6) | |||
Positive association between IQ and BF | 4 (30) | A—1 (25) | |
B—0 (0) | |||
C—3 (75) | |||
Initial positive association which became negative after adjustment for confounders. | 2 (15) | A—0 (0) | |
B—2 (100) | |||
C—0 (0) | |||
Initial positive association weakened after adjustment for confounders but remained statistically significant | 1 (8) | A—1 (100) | |
B—0 (0) | |||
C—0 (0) | |||
Developed countries (n=71) | No association between IQ and BF | 15 (21) | A—4 (26.6) |
B—7 (46.6) | |||
C—4 (26.6) | |||
Positive association between IQ and BF | 24 (34) | A—9 (37.5) | |
B—7 (29.2) | |||
C—8 (33.3) | |||
Initial positive association which became negative after adjustment for confounders. | 16 (22.5) | A—6 (37.5) | |
B—6 (37.5) | |||
C—4 (25) | |||
Initial positive association weakened after adjustment for confounders but remained statistically significant | 16 (22.5) | A—13 (81.25) | |
B—2 (12.5) | |||
C—1 (6.25) |
Developing: Refs. 15 ,21 ,33–36 ,38 ,63 ,69 ,72 ,73 ,97 ,100
Developed: Refs. 9 ,13 ,22–32 ,37 ,39–62 64–71 74–96 ,98 ,99 ,101
BF, breastfeeding.