Associated factors of first-birth interval among women in reproductive age, addressing maternal and child health

Table 2 Results of the univariate Cox proportional hazards analysis (crude analysis) to evaluated factors related to FBI

	\(\beta\)	HR	SE (β)	95% CI for HR	P-value
Women’s predictors
Women’s age at marriage	− 0.338	1.402	0.421	1.29–2.92	< 0.001
Age at the first menstruation	− 0.461	1.587	0.383	1.14–2.73	0.002
Women’s drug use vs. none	− 0.199	1.221	0.122	0.11–2.04	0.071
Women’s BMI	0.594	1.812	0.484	1.47–2.92	0.001
Women’s underlying disease	− 0.208	1.232	0.118	0.74–1.72	0.111
High school and Diploma vs. illiterate	− 0.167	1.182	0.187	0.45–1.66	0.141
University education vs. illiterate	0.427	1.534	0.323	1.45–2.72	0.005
Contraception use	0.963	2.621	0.254	1.21–2.92	< 0.001
Night job of mother vs. daily	− 0.158	1.172	0.122	0.27–1.91	0.091
Husband’s predictors
Husband’s age at marriage	− 0.753	2.124	0.014	1.71–2.42	< 0.001
High school and Diploma vs. illiterate	− 0.439	1.552	0.098	0.27–2.14	0.084
University education vs. illiterate	0.423	1.526	0.452	1.41–2.56	0.001
Husband drug use vs. None	0.489	1.632	0.152	0.28–2.21	0.132
Night job of husband vs. daily	− 0.203	1.226	0.221	0.24–1.82	0.142
Family predictors
Family marriage vs. not family	− 0.196	1.217	0.119	0.32–2.21	0.134
Rural residence vs. town	− 0.942	2.564	0.488	1.37–3.11	0.003
Income sufficiency vs. not sufficient	0.885	2.423	0.158	1.29–3.02	< 0.001
Having engagement period vs. none	− 0.653	1.921	0.045	1.62–3.33	0.002

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