TABLE 4.

Risk of bias assessment (QUIPS)

	Study participation	Study attrition	Prognostic factor measurement	Outcome measurement	Study confounding	Statistical analysis and reporting	Overall RoB
Child factors
GA
Preterm
Yaari et al., 2018	?	+	+	?	+	+	H
Term
Espel et al., 2014	+	?	?	+	+	+	H
Post‐term
Field et al., 1978	?	N/A	‐	+	‐	‐	H
Birthweight Low birthweight
Datar & Jacknowitz, 2009	+	+	+	+	+	+	L
Grantham‐McGregor et al., 1998	+	+	+	+	+	+	L
Normal birthweight
Lung et al., 2009a	+	+	+	?	+	+	H
Twin
Nan et al., 2013	+	‐	+	?	+	+	H
Brouwer et al., 2006	?	N/A	+	?	?	‐	H
Goetghebuer et al., 2003	?	‐	+	?	+	+	H
Wilson & Harpring, 1972	‐	‐	‐	+	‐	‐	H
Weight, length and head circumference
Scharf et al., 2016	?	?	+	+	+	?	H
Overweight
Slining et al., 2010	+	+	+	+	+	+	L
Proportionately larger head
Bartlett, 1998	+	‐	+	+	‐	‐	H
Afro‐American background
Capute et al., 1985	?	‐	?	‐	‐	‐	H
Motivation to move
Atun‐Einy et al., 2013	‐	N/A	‐	+	‐	?	H
Environmental factors
Sleep position
Prone sleeping
Majnemer and Barr, 2006	‐	?	?	+	+	+	H
Davis et al., 1998	+	?	+	?	?	+	H
Supine sleeping
Lung and Shu, 2011	?	?	+	?	+	+	H
Ratliff‐Schaub et al., 2001	?	‐	?	+	+	‐	H
Breastfeeding
Jardí et al., 2018	+	N/A	+	+	+	+	L
Michels et al., 2017	+	N/A	+	?	+	+	H
Morris et al., 1999	+	+	+	+	+	+	L
Oddy et al., 2011	?	?	?	?	+	+	H
Maternal depression
Smith‐Nielsen et al., 2019	?	+	+	+	?	+	H
Sutter‐Dallay et al., 2011	+	?	?	+	+	+	H
Maternal mental health
Lung and Shu, 2011	+	?	+	?	+	+	H
Adolescent mother
de Borba and Valentini, 2015	‐	N/A	+	‐	?	‐	H
Parental mental health
Lung et al., 2009b	+	+	+	?	+	+	H
Parental neonatal perception
Hernández‐Martínez et al., 2011	+	N/A	+	+	+	?	H
Babywalker
Siegel and Burton, 1999	?	+	?	+	?	?	H
Daycare attendance
Souza et al., 2010	‐	N/A	?	+	‐	‐	H
Season of birth winter
Tsuchiya et al., 2012	?	+	+	?	+	+	H
Cameroonian versus German culture
Vierhaus et al., 2011	?	?	+	?	+	+	H
Multiple factors
Bjarnadóttir et al., 2019	+	+	+	?	+	+	H
Flensborg‐Madsen & Mortensen, 2017	+	‐	+	?	+	?	H
Pereira et al., 2016	‐	‐	?	+	+	+	H

Note. L = low risk of bias (RoB), H = high RoB; ‐ = not reported, + = reported, ? = not sure; N/A = not applicable.