Table 2.

Linear regression output on the predictors of serum retinol concentrations (μmol/L) among pregnant women in China

Independent variable	Unstandardized coefficient	t-statistic	P value
Constant	1.61
age (years)	−0.01	−2.34	0.02
Gestational age (months)	−0.08	−3.68	0.00
Region strataa	−0.05	−2.42	0.02
Anemia(0 = yes 1 = no)	−0.11	−2.54	0.01
Income+	0.05	2.53	0.01

^a:1 = large cities 2 = small to medium cities 3 = general rural areas 4 = poor rural areas

+:1:<10,000;2:10,000–20,000;3:20,000–30,000;4:≥30,000