Table 3. Overview of the Meta-Analysis of the Included Cohort Studies Categorized as Upper-Middle-Income and Upper-Income Countries^*.

Risk factor	n	K	Pooled odds ratio (95% Cl)	Chi-square2 value	I2 value
Upper-middle-income countries
Low birthweight31,51	822	2	0.83 (0.49, 1.41)	1.83	45
Increased baseline salivary levels of Streptococcus mutans18,31	394	2	9.21 (4.97, 17.07)	0.22	0
Presence of enamel defects19,31	453	2	14.62 (6.10, 35.03)	0.00	0
Night bottle feeding49,64	564	2	0.62 (0.49, 0.78)	1.91	48
Night breastfeeding31,49	449	2	1.28 (1.11, 1.47)	1.54	35
Gender (male)51,64	937	2	1.26 (0.85, 1.88)	3.45	71
Toothbrushing at least once a day31,49	449	2	1.36 (1.08, 1.72)	0.60	0
Brushing with fluoride toothpaste51,64	937	2	1.03 (0.75, 1.42)	0.47	0
Sugar snacks at least once a day31,49	449	2	0.69 (0.16, 3.00)	0.95	84
Low maternal age (<25 years)31,51	822	2	0.65 (0.45, 0.94)	1.75	43
High-income countries
Low maternal education (≤9 years)2,17,56,63,66,70,75	5,885	8	1.84 (1.14, 2.08)	31.49	78
Low birthweight (<2,500 g)56,63	1,857	2	1.70 (0.89, 3.23)	0.00	0
Smoking during pregnancy1,63	1,580	2	1.33 (0.74, 2.39)	2.53	60
Increased baseline salivary levels of S. mutans30,42,45,55,73	2,812	5	3.83 (1.81, 8.09)	47.96	92
Increased consumption of soda pop25,56	886	2	1.12 (1.03, 1.23)	0.18	0
Maternal age (<25 years)1,17,63	2,565	3	1.26 (0.65, 2.45)	17.43	89
Toothbrushing at least once a day2,25,66,67	2,328	4	0.91 (0.55, 1.51)	6.69	55
Visible plaque present42,70,72	1,106	3	3.1 (2.00, 4.80)	0.52	0
Poor oral hygiene67,72	394	2	3.12 (1.77, 5.49)	0.28	0
Night bottle feeding37,42,58	592	3	1.15 (0.44, 3.04)	14.91	87
Age at dental exam >1 year2,25,66,67	2,328	2	1.68(1.06, 2.66)	0.78	0
Liquids in bottle other than milk58,68	421	2	1.27 (0.83, 1.94)	2.04	51
Presence of lactobacilli37,55	1,728	2	2.18 (2.03, 2.34)	1.13	11
Gestational age <37 weeks29,63	1,445	2	0.67 (0.14, 3.12)	3.50	71
Gender (males)17,30,39,63	2,727	4	0.98 (0.80, 1.19)	2.01	0
Age started brushing ≥12,53	836	2	2.12 (1.49, 3.01)	0.00	0
Brushing <1x/day17,53,54,75	32,984	4	1.08 (0.61, 1.92)	12.39	76
Dentinal caries (dmft >0)66,70	2,268	2	4.21 (2.18, 8.16)	0.42	0
No topical fluoride application53,54	31,768	2	1.50 (1.39, 1.63)	1.22	18
Frequent consumption of sweetened foods2,54	31,472	2	3.14 (0.89, 11.04)	3.01	67
Intake of sugar snacks daily2,30,54	31,831	3	1.56 (1.42, 1.71)	0.68	0
Intake of sugar beverages2,42,67,68,73	1,298	5	1.67 (0.25, 3.92)	46.18	91
Socioeconomic status25,39	412	2	0.46 (0.28, 0.74)	0.05	0

^*n=number of participants; K=number of studies; dmft=decayed, filled, and missing primary teeth.