Materials and Methods: In a cross-sectional study, 610 married women aged 15 to 49 years were selected by the stratified random sampling and a structured questionnaire was used in 2017. Women?s first birth intervals were compared in terms of some demographic and socio-economic factors by Kaplan-Meier (KM) estimates and Log-Rank test for univariate and Cox model for multivariate survival analysis using SPSS version 22.0.

Results: The mean of women?s first birth intervals was 3.181±0.101 years. Women?s educational level and social insecurity had significant effects on the first birth interval (P value <0.05). By increasing educational level and social insecurity, the first birth interval also increased. Women with ?secondary and high school? and ?MS and PhD? educational levels had the shortest and longest first birth intervals, respectively.

Conclusions: According to results, unless governments provide the condition of social security, reducing the interval between marriage age and childbearing will not be attained.