Abstract
BACKGROUND: The first-birth interval directly influences family size and maternal and child mortality. The objective of this study is to investigate factors associated with the time of the first-birth after the first marriage among women in Iran. METHODS: In this cross-sectional study, the first birth history of 1350 women aged 15-49 years was collected in Kerman (southern Iran) in 2018. To assess the predictor variables of the first-birth interval and calculate the adjusted hazard ratios, multivariate Cox regression was used. The P-value < 0.05 was considered as significant. The statistical analysis of data was performed using SPSS version 22. RESULTS: The average of the first-birth interval was 2.5 ∓ 0.8 years. Woman's age at marriage (HR 1.48, 95% CI 1.32-2.48), husband's age at marriage (HR 1.88, 95% CI 1.62-2.03), age at the first menstruation (HR 1.53, 95% CI 1.24-2.53), being rural residents (HR 2.041, 95% CI 1.26-2.95), and having engagement period (HR 1.85, 95% CI 1.52-3.05) were associated with short first-birth interval, and woman's BMI (HR 1.72, 95% CI 1.54-2.77), woman's university educational level (HR 1.47, 95% CI 1.35-2.57), husband' s university educational level (HR 1.39, 95% CI 1.32-2.51), contraception use (HR 2.28, 95% CI 1.12-2.86) and income sufficiency (HR 2.25, 95% CI 1.12-2.96) were associated with long first-birth interval. CONCLUSIONS: Being a rural resident is the most influential predictor of short first-birth interval and income sufficiency is the most influential predictor of long first-birth interval.