Analysis	Method
Dealing with missing data	For studies missing > 40% of their data, we intended to conduct sensitivity analysis to explore the nature of the missing data, when available data permitted.
Subgroup analysis and investigation of heterogeneity	We planned to conduct the following subgroup analyses: Age of mother at time of birth (younger vs older; i.e. 21 years of age and under vs over 21 years of age); Type of feeding (bottle fed vs breast fed); Atopy (lower vs higher risk of atopy); Short‐term and long‐term follow‐up (< 4 weeks of treatment vs ≥ 4 weeks of treatment); and Low‐quality trials versus high‐quality trials (allocation concealment vs lack of allocation concealment; blinding vs lack of blinding) (Savino 2012). These analyses would have been exploratory as they involved non‐experimental (cross‐study) comparisons, and given the large numbers of subgroup analyses, they may lead to misleading conclusions (Yusuf 1991; Oxman 1992).
Sensitivity analysis	We planned to assess the sensitivity of findings for any imputed data to explore the possible impact of missing data (Savino 2012).