Table 2.

Quality assessment of studies included in the meta-anlayses

Study	Study type	Selection	Comparability	Outcome/Exposure
Jones et al [7]	Cohort	***		***
Milligan et al. [12]	Cohort	****	*	***
Lim et al. [13]	RCT	***	**	**
Szaflarski [8]	RCT	***	**	***
Taylor et al. [14]	Cohort	***	**	**
Murphy-Human et al. [15]	Cohort	***	**	***