Prenatal incidence of cleft lip/palate and cocaine abuse in parents: a systematic review and meta-analysis

BMC Oral Health

Table 2 Demographic variables assessed across the included articles

Study ID	Year	Region	Protocol	Sample size (n)	Assessed period (in years)
Fries et al. [15]	1993	USA	Case-control	32	5
Hume et al. [16]	1997	USA	Case-control	119	9
Stafford et al. [17]	1994	USA	Case-control	80	0.75
Van Gelder et al. [18]	2009	USA	Cross-sectional	15,208	6

ISSN: 1472-6831