Table 2.

Multivariate logistic regression analysis of influencing factors of serum vitamin D level in pregnant women.

Influencing factor	Variable	OR	95% CI of OR	P
Age (yr old)	15–25	1.000	---	---
	25–35	1.072	0.723∼1.285	.322
	35–46	1.113	0.809∼1.326	0.253
Gestational age (wk)	10–13	1.000	---	---
	13–28	1.275	0.921∼1.632	.086
	28–32	1.426	1.105∼1.712	.032∗
Season	Winter and spring	1.000	---	---
	Summer and autumn	4.383	2.532∼5.967	<.001∗
Education level	Junior high school and below	1.000	---	---
	High school and above	2.296	1.315∼3.368	.021∗
Weekly time outdoors (hr)	<10	1.000	---	---
	≥10	1.822	1.263∼2.385	.026∗
Vitamin D supplement	Yes	1.000	---	---
	No	5.264	2.182∼8.361	<.001∗
Calcium supplement	Yes	1.000	---	---
	No	1.035	0.812∼1.186	.403
Trace element supplement	Yes	1.000	---	---
	No	3.662	1.864∼5.386	<.001∗