Table 3.

Frequency and proportion of exposure ecological levels, constructs, and measurement characteristics (k = 122)

Characteristic		Number of studies	Proportion (of total k)*
Ecological level	Microsystem	104	85.2%
	Mesosystem	17	13.9%
	Exosystem	5	4.1%
	Macrosystem	5	4.1%
Construct	Microsystem
	Child attachment security	10	8.2%
	Caregiver felt bond	37	30.3%
	Responsive caregiving	38	31.1%
	Caregiver-child interaction	10	8.2%
	Co-caregiving	5	4.1%
	Caregiver-partner relationship	25	20.5%
	Intimate partner violence	3	2.5%
	Caregiver-sibling relationship	2	1.6%
	Mesosystem
	Social stress	3	2.5%
	Social support	15	12.3%
	Exosystem
	Perceived neighbourhood safety	1	0.8%
	Early discharge from hospital	1	0.8%
	Rooming in	2	1.6%
	Job satisfaction	1	0.8%
	Macrosystem
	Cultural differences	5	4.1%
Timing of assessment	Antenatal	54	44.3%
	Postnatal	74	60.7%
Trimester (if antenatal)	1	4	3.3%
	2	16	13.1%
	3	25	20.5%
Child age (if postnatal)	< 1 month	8	6.6%
	> = 1, < 6 months	34	27.9%
	> = 6, < 12 months	25	20.5%
	> = 12, < 24 months	17	13.9%
	> = 24, < 48 months	4	3.3%
Measurement mode	Maternal report	61	50.0%
	Paternal report	17	13.9%
	Parent report (unspecified/mixed)	1	0.8%
	Researcher observation	53	43.4%
	Other	10	8.2%

^*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)