Table 2.

Frequency and proportion of outcome constructs and measurement characteristics (k = 122)

Characteristic		Number of studies	Proportion (of total k)*
Construct	Child attachment security	33	27.0%
	Caregiver felt bond	46	37.7%
	Responsive caregiving	38	31.1%
	Caregiver-child interaction	24	19.7%
Caregiver	Mother	106	86.9%
	Father	31	25.4%
	Both/mixed	9	7.4%
	Teacher	1	0.8%
Timing of assessment	Antenatal	7	5.7%
	Postnatal	115	94.3%
Trimester (if antenatal)	2	1	0.8%
	3	4	3.3%
Child age (if postnatal)	< 1 month	6	4.9%
	> = 1, < 6 months	42	34.4%
	> = 6, < 12 months	26	21.3%
	> = 12, < 24 months	51	41.8%
	> = 24, < 48 months	17	13.9%
Measurement mode	Maternal report	42	34.4%
	Paternal report	11	9.0%
	Researcher observation	79	64.8%

^*The proportion of the total number of studies with each level of a characteristic often do not add up to 100%; this is because of missing data and/or studies that included more than one level of a characteristic (for example, studies that assessed an outcome at multiple timepoints, or studies that assessed more than one outcome construct)