Table 2. Association between secondhand smoking and preterm birth before 37 weeks in multivariable logistic regression analysis.

Variables	AOR (95%CI)	P value
Maternal age	1.04 (1.00–1.08)	< 0.01
BMI	1.04 (0.99–1.10)	> 0.05
Occupation (farmer)	1.03 (0.66–1.61)	> 0.05
Education (primary school)	1.42 (0.88–2.29)	> 0.05
Parity (parous)	0.48 (0.30–0.76)	< 0.01
ANC visits (≥4)	0.53 (0.35–0.79)	< 0.01
History of preterm birth	10.4 (4.1–26.3)	< 0.001
Prenatal bleeding	22.6 (5.2–97.7)	< 0.001
Preeclampsia/Eclampsia	9.55 (2.80–32.4)	< 0.001
Secondhand smoking	1.92 (1.31–2.81)	< 0.01

AOR, adjusted Odds Ratio; BMI, Body mass index; ANC, Antenatal care