using cox model on tempo and influential factors in women of bahram abad village

objective: tempo is the average waiting time to next birth for a woman. role of fertility as the most important phenomenon determining population fluctuations due to the studies of it compared with other demographic phenomena be important and review the multifarious socioeconomic factors of it share  a large effective population studies. general purpose of this study is fitting the cox model to determine factors that influence the birth of second child and too calculate the tempo in second to eight births on bahram abad rural women. materials and methods: population under study are all married women with 15-45 years old that live in bahram abad village's and have had at least two children. this study is a cross sectional study. in the present study birth of each child is considered as a disaster and because survival data generally have not symmetrical distribution then the cox regression model  (proportional hazard model) is used for effects of variables on survival and hazard. results: in this research 228 mothers were studied and they have had 669 children. mean number of children is 3and 42% of these children are girls and others are boys. maximum tempo is from labor fifth to labor sixth (63.32) and the least is from the sixth to seventh of childbirth (57). conclusion: in the final model from available variables only the age difference of parent had a positive impact on tempo.