Table 6.

Association of combined GSTM1 and GSTT1 genotype and Hg level with birth weight.

Exposure period of total Hg level (log scale of μg/L)	Genotype			Adjusteda
		Unadjusted		Full sample		Subsample excluding preterm births
		β	95% CI	β	95% CI	β	95% CI
Early pregnancy	Both presentb	130.7	−49.8 to 311.1	39.6	−144.8 to 224.0	39.6	−144.8 to 224.0
	Either nullc	−27.3	−141.0 to 86.5	−129.4	−232.8 to −26.1	−99.2	−206.7 to 8.4
	Double nulld	−27.6	−143.9 to 88.8	−39.9	−155.4 to 75.7	−26.0	−142.6 to 90.5
Late pregnancy	Both presentb	104.4	−82.1 to 290.9	46.2	−134.7 to 227.1	46.2	−134.7 to 227.1
	Either nullc	−33.11	−157.1 to 90.9	−74.8	−186.6 to 37.0	−29.9	−143.9 to 84.1
	Double nulld	−62.8	−169.2 to 43.6	−102.8	−205.4 to −0.2	−89.1	−193.2 to 15.1
Cord blood	Both presentb	13.3	−193.0 to 219.7	−13.6	−222.5 to 195.4	−13.6	−222.5 to 195.4
	Either nullc	−17.6	−138.9 to 103.6	−93.9	−203.2 to 15.3	−48.2	−161.5 to 65.2
	Double nulld	−105.0	−239.1 to 29.1	−138.4	−268.8 to −8.0	−117.9	−251.3 to 15.5

^aMultivariate regression model included gestational age, prepregnancy BMI, maternal age, mother’s educational level, infant sex, parity, and weight gain during pregnancy as covariates.

^bBoth GSTM1 and GSTT1 is present.

^cEither GSTM1 or GSTT1 is null.

^dBoth GSTM1 and GSTT1 are null.