Table 4.

Interactions between SNPs of MTHFD1 gene and maternal smoking detected by logistic regression

SNPs	Passive smoking before pregnancy			Passive smoking in the first trimester
	aOR (95%CI)	P	FDR_P	aOR (95%CI)	P	FDR_P
rs1950902 (additive)	1.09(0.49–2.45)	0.830	0.830	1.13(0.44–2.91)	0.800	0.800
rs2236225 (additive)	3.65(1.62–8.22)	0.002	0.003	3.17(1.15–8.75)	0.026	0.043
rs2236222 (additive)	0.32(0.18–0.60)	< 0.001	< 0.001	0.43(0.23–0.83)	0.011	0.035
rs11849530 (additive)	1.28(0.58–2.82)	0.538	0.673	1.82(0.72–4.60)	0.207	0.259
rs1256142 (dominant)	0.24(0.12–0.45)	< 0.001	< 0.001	0.45(0.24–0.85)	0.014	0.035

Abbreviations: aOR adjusted odds ratio; CI confidence interval; SNPs single nucleotide polymorphisms; MTHFD1 methylenetetrahydrofolate dehydrogenase 1; FDR_P false discovery rate P value

^aAdjusted for residence location, maternal education level (years), annual income in the past 1 year (RMB), history of adverse pregnancy outcomes, consanguineous marriage, history of congenital malformations in family, cold or fever in the periconceptional period, and personal lifestyle and habit in the periconceptional period including drinking alcohol, drinking tea, living near environmental pollution source, dyeing hair or perming and folate use

^bFDR_P < 0.1 was considered to indicate a statistically significant difference