Table 6.

Determinants of maternal plasma B vitamin status in pregnancy week 18 by multiple linear regression (n=2871)

Independent variables	Serum Folate, nmol/L		Serum Cobalamin, pmol/L		Plasma PLP, nmol/L		Plasma Riboflavin, nmol/L		Plasma tHcy, μmol/L		Plasma MMA, μmol/L		Plasma 3-OH-kynurenine, μmol/L
	B	p	B	p	B	p	B	p	B	p	B	p	B	p
Use of folic acida	6.0	<0.001	14	0.003	7.2	<0.001	1.9	0.001	−0.81	<0.001	−0.003	0.16	−1.5	0.001
Current daily smoking, 0–1	−1.0	<0.001	−10	0.008	−3.2	<0.001	−0.7	0.12	0.30	0.001	−0.003	0.07	−1.3	<0.001
Parityb	−1.1	<0.001	−4	0.11	−1.6	0.004	−1.0	0.001	−0.03	0.62	−0.002	0.14	0.2	0.53
Agec	2.3	<0.001	13	0.004	2.7	0.005	0.3	0.58	0.07	0.53	0.005	0.02	0.3	0.46

^aUse of folic acid supplement any time from 4 weeks before pregnancy up to pregnancy week 17

^bParity, categorized; 0, 1, 2, 3+

^cAge, categorized; <25 y, 25–29 y, 30–34 y, >34 y