Study	Reason for exclusion
Belykh 2014	Reported as a conference abstract. Iodine given to mother during pregnancy and lactation. Likely that infant supplementation given via mother and iodine was not added to breast milk directly.
Bouhouch 2013	Likely to be a trial restricted to term rather than preterm infants. Compared iodine supplementation for mothers versus iodine supplementation for infants (i.e. maternal supplementation was the control rather than no supplementation).
Kartoğlu 2014	Gestation of participants not specified, and trial compared treatment of infants with congenital hypothyroidism.
Mohammed 2015	Cluster randomised controlled trial of iodised salt given to pregnant women (rather than infants) in Ethiopia.
Wang 2013	Chinese language report with English abstract. Likely to have been a cluster randomised controlled trial of effect of community‐based iodine supplementation for children up to 3 years old on neurodevelopment.