. 2016 Feb 12;16:142. doi: 10.1186/s12889-016-2816-4

Table 3.

Risk of low birth weight associated with maternal urinary manganese levels, stratified by maternal age

Manganese levels^a	Age < 28 years old (n = 392)			Age ≥ 28 years old (n = 424)			P for heterogeneity
Manganese levels^a	Ca/Co	OR^b (95 % CI)	OR^c (95 % CI)	Ca/Co	OR^b (95 % CI)	OR^c (95 % CI)	P for heterogeneity
Tertile 1	31/98	1.80 (0.91, 3.56)	1.88 (0.74, 4.80)	23/106	0.72 (0.39, 1.34)	0.84 (0.31, 2.24)	0.19
Tertile 2	17/98	1.00	1.00	31/106	1.00	1.00
Tertile 3	50/98	3.14 (1.67, 5.92)	2.74 (1.07, 7.03)	52/106	1.69 (0.98, 2.90)	1.98 (0.82, 4.74)

Abbreviations: ca/co, numbers of cases and controls; CI confidence interval; OR odds ratio

^a Manganese levels (μg/g creatinine): age < 28 years, tertile 1 (<0.30), tertile 2 (0.30–1.08), tertile 3 (≥1.09); age ≥ 28 years, tertile 1 (<0.28), tertile 2 (0.28–1.21), tertile 3(≥1.22)

^b Crude odds ratio

^c Adjusted for gestational age, household income, pre-pregnancy body mass index, parity, passive smoking, and gestational hypertension