Maternal Serum Concentrations of Selenium, Copper, and Zinc during Pregnancy Are Associated with Risk of Spontaneous Preterm Birth: A Case-Control Study from Malawi

Table 3

Unadjusted and adjusted estimates for being preterm (complete case analysis).

Variable	Characteristic	Unadjusted				Adjusted
		OR	95% CI		value	OR	95% CI		value
Maternal age	Yearly increase	0.94	0.89	0.99	0.012	0.99	0.92	1.07	0.862
Herbal medication	No
	Yes	2.55	1.16	5.98	0.024	2.44	0.97	6.52	0.064
Unit increase in selenium	Unit	1.02	1.00	1.03	0.063	1.01	0.99	1.03	0.234
Unit increase in copper	Unit	2.38	1.31	4.54	0.006	1.62	0.80	3.32	0.184
Unit increase in zinc	Unit	8.56	1.83	46.10	0.009	6.88	1.25	43.67	0.032
Gravidity	1-2	Ref
	2-5	0.45	0.23	0.85	0.015	0.68	0.29	1.61	0.381
	≥6	0.74	0.22	2.51	0.624	1.14	0.21	6.12	0.874

OR: odds ratio; CI: confidence interval; Ref: reference. Simple and multivariable logistic regression used.