Study inclusion and exclusion flow diagram. a Exclusion criteria: duplication, no apparent relevance. b First-level inclusion criteria: articles that reported an association between breastfeeding and SIDS. c Second-level inclusion criteria: see criteria listed in Table 1; an additional study was excluded for not providing ORs that could be used in calculating an SOR.
Studies were scored on the following criteria: (1) an appropriate definition for SIDS; (2) autopsies performed in >98% of cases; (3) an adequate description of SIDS ascertainment in the study population; (4) matched control subjects; (5) an adequate description of the process of control selection; and (6) inclusion of sufficient data to calculate ORs and 95% CIs or the actual ORs and CIs were provided. NA indicates not available, not provided.
↵a Covariates: 1, maternal age; 2, parity; 3, birth weight; 4, infant exposure to tobacco smoke (before or after delivery); 5, factors related to socioeconomic status; 6, infant sleep position; 7, bed-sharing; 8, infant age; 9, infant gender; 10, gestation; 11, marital status; 12, race/ethnicity; 13, factors related to prenatal care; 14, factors relating to surface on which infant was placed; 15, pillow/cushion use; 16, factors related to overheating; 17, postneonatal infant health problems; 18, pacifier use; 19, other.
↵b Time to interview was defined as time from infant's death or identification of controls to interview with parents.
↵c ORs in the article were provided for intervals of breastfeeding duration; thus, we could not identify an OR to use in calculating the SOR for this meta-analysis.