TABLE 4.

Relative odds of early pregnancy loss by preconception DDT and B-vitamin status in 385 conceptions from 280 nonsmoking, nulligravid women, 1996–1998¹

	Low DDT			High DDT
	Total, n	Cases, n (%)	Adjusted OR (95% CI)	Total, n	Cases, n (%)	Adjusted OR (95% CI)	P-effect modification
Vitamin B-12, pmol/L							0.952
Normal	149	40 (26.9)	1.00 (reference)	177	62 (35.0)	1.52 (0.96, 2.41)
<258	33	8 (24.2)	1.17 (0.48, 2.82)	26	10 (38.5)	1.71 (0.72, 4.08)
Linear vitamin B-12, /IQD	—	—	0.92 (0.65, 1.32)	—	—	1.02 (0.69, 1.51)	0.713
Vitamin B-6, nmol/L							0.572
Normal	140	34 (24.3)	1.00 (reference)	143	48 (33.6)	1.60 (0.97, 2.64)
<30	42	14 (33.3)	1.74 (0.89, 3.41)	60	24 (40.0)	2.11 (1.05, 4.25)
Linear vitamin B-6, /IQD	—	—	0.73 (0.46, 1.16)	—	—	0.56 (0.36, 0.88)	0.433
Folate, nmol/L							0.282
Normal	150	40 (26.7)	1.00 (reference)	161	55 (34.2)	1.35 (0.83, 2.19)
<6.8	32	8 (25.0)	0.83 (0.37, 1.83)	42	17 (40.5)	1.96 (0.98, 3.93)
Linear folate, /IQD	—	—	1.02 (0.79, 1.33)	—	—	0.55 (0.38, 0.79)	0.0063
No. of B-vitamin deficiencies							>0.052
0	101	25 (24.8)	1.00 (reference)	113	36 (31.9)	1.42 (0.80, 2.52)
1	60	18 (30.0)	1.38 (0.69, 2.75)	56	24 (42.9)	2.34 (1.25, 4.38)
≥2	21	5 (23.8)	1.18 (0.47, 2.96)	34	12 (35.3)	1.77 (0.70, 4.44)

¹Adjusted for maternal age, education, BMI, perceived life stress, tea drinking habit, occupational exposure to dust and noise, and husband smoking. The IQD was 159.3 pmol/L for vitamin B-12, 17.8 nmol/L for vitamin B-6, and 4.8 nmol/L for folate. DDT, 1,1,1-trichloro-2,2,bis(p-chlorophenyl)ethane; IQD, interquartile distance.

²Estimated in the adjusted model with DDT (low or high) and vitamin (normal or deficiency) and the interaction of the two.

³Estimated in the adjusted model with DDT (low or high) and vitamin (linear term) and the interaction of the two.