Mode of transmission	Number of Studies	Number of babies
Horizontal (Person to Person)[@34571; @34572; @34573; @34577; @34586; @34593; @34594; @34597; @34599; @34600; @34603; @34606; @34608; @34610; @34611; @34614]	16	17
Vertical transmission[@34574; @34607; @34608; @34609; @34619]	5	11
Uncertain about mode of transmission[@34578; @34587; @34601; @34613; @34616]	3	10