Table 2.

Multivariable linear regression analysis of the determinants of plasma homocysteine, with plasma homocysteine as a continuous dependent variable (n 7587)

Variable	Effect	95 % CI	P-value*
Demographic characteristics
Age (rcs, three knots)			0·0013
34 v. 27 years	−0·027	−0·070, 0·016
Race			<0·0001
Caucasian	Reference
African	−0·370	−0·561, −0·179
Middle Eastern	−0·438	−0·594, −0·282
Asian	−0·468	−0·588, −0·349
Other	−0·405	−0·612, −0·197
Education			0·3987
College/university completed v. less than completed	−0·032	−0·105, 0·042
Health indicators
BMI (rcs, three knots)			0·0103
27·3 v. 21·1 kg/m2	−0·070	−0·119, −0·022
Diabetes			0·6197
Yes v. no	−0·056	−0·279, 0·166
Chronic hypertension			0·0001
Yes v. no	0·502	0·250, 0·754
Pregnancy characteristics
Nulliparous			<0·0001
Yes v. no	0·140	0·073, 0·207
Smoking			<0·0001
No	Reference
Second-hand exposure	0·298	0·097, 0·499
Med/light smoker (<10 cigarettes per day)	0·418	0·297, 0·539
Heavy smoker (≥10 cigarettes per day)	0·864	0·705, 1·022
Hormonal birth control prior to conception			0·1747
No	Reference
Oral	−0·046	−0·108, 0·015
Injection or IUD	0·091	−0·088, 0·270
History of PMC (pre-eclampsia, placental abruption, SGA, stillbirth/loss)			0·0078
Yes v. no	−0·124	−0·215, −0·033
Folic acid supplementation			<0·0001
None	Reference
>0 and ≤1 mg	−0·310	−0·442, −0·178
>1 mg	−0·329	−0·476, −0·181
Homocysteine metabolism
Gestational age at bloodwork (rcs, five knots)			<0·0001
13·4 v. 12·4 weeks	0·016	−0·063, 0·095
Serum folate (rcs, five knots)			<0·0001
45·1 v. 30·6 nmol/l	0·137	0·065, 0·210

rcs, restricted cubic spline; PMC, placenta-mediated complication.

^*Wald test of most meaningful hypotheses, pooled across multiple imputation datasets.