PM2.5 constituent exposures and maternal circulatory homocysteine in early pregnancy

Table 3 Associations of an IQR increase in average PM_2.5 and constituent exposures during the post-conception period with percentage changes in serum Hcy in all participants, EPL group, and NEP group

Parameter	All participants (n = 324)		EPL (n = 162)		NEP (n = 162)
Parameter	β (95% CI)	p-value	β (95% CI)	p-value	β (95% CI)	p-value
Pollutant concentration
PM_2.5	11.5 (-3.9, 29.5)	0.151	20.2 (-6.7, 54.9)	0.153	5.6 (-12.4, 27.2)	0.567
BC	22.7 (7.3, 40.3)	0.003	37.3 (10.6, 70.3)	0.004	9.7 (-8.3, 31.3)	0.310
OM	19.4 (3.9, 37.1)	0.012	31.5 (4.6, 65.5)	0.019	9.2 (-8.7, 30.7)	0.334
NO₃^–	13.4 (1.2, 27.1)	0.031	24.8 (2.6, 51.8)	0.027	6.3 (-7.8, 22.5)	0.397
NH₄⁺	13.3 (2.5, 25.2)	0.015	24.2 (4.7, 47.3)	0.013	6.2 (-6.4, 20.4)	0.351
SO₄^2–	11.7 (4.9, 19.0)	< 0.001	18.5 (6.8, 31.6)	0.002	6.7 (-1.7, 15.7)	0.118
Constituent residual
BC	6.8 (2.4, 11.4)	0.002	10.5 (3.3, 18.1)	0.004	2.7 (-3.1, 8.8)	0.369
OM	4.3 (0.4, 8.3)	0.030	5.7 (-0.4, 12.3)	0.067	2.2 (-2.9, 7.6)	0.404
NO₃^–	4.4 (-0.2, 9.3)	0.063	7.3 (-0.5, 15.6)	0.065	2.4 (-3.6, 8.8)	0.440
NH₄⁺	5.8 (1.2, 10.5)	0.012	9.2 (1.8, 17.3)	0.015	3.0 (-2.9, 9.3)	0.319
SO₄^2–	9.0 (4.6, 13.4)	< 0.001	13.0 (5.9, 20.5)	< 0.001	5.6 (0.1, 11.4)	0.047

Note: The independent variables in the multivariable linear regression models included average concentration of PM_2.5 or each constituent, or average residual of each constituent, the natural logarithm of serum 5-methyltetrahydrofolate (Ln5-MeTHF), all demographic characteristics presented in Table 1, temperature, relative humidity, and group (EPL or NEP). The IQRs of concentration of PM_2.5, BC, OM, NO₃^–, NH₄⁺, and SO₄^2– in the analyses were 29, 1.1, 5.8, 6.7, 3.6, and 2.5 µg/m³, respectively. The IQRs of residual of BC, OM, NO₃^–, NH₄⁺, and SO₄^2– in the analyses were 0.2, 0.9, 1.5, 0.9, and 1.1, respectively

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