duration and determinants of birth interval in yazd, iran: a population study

background: short birth intervals have been associated with adverse health outcomes, including infant, child and maternal mortality. objective:  we aimed to investigate the duration and determinants of inter birth intervals among women of reproductive age in yazd, iran. materials and methods:  a cluster sampling technique was used to select 400 ever-married women aged 15-49 years in yazd, islamic republic of iran. data were obtained by interview questionnaire and analyzed with life table, kaplan-meier survival and cox regression analyses. results:  the mean duration of inter birth interval was 49.76 (standard error 1.82) months (95% ci: 46.19-53.34 months) with a median of 39. in 28.5% of women the birth interval was <2 years, in 28% it was 3-5 years and in 25.5% it was ≥6 years. among explanatory variables of interest, age of marriage, and woman's education were significant predicators of the birth interval. women who stated an ideal preference of two children constituted 59.9% of the sample and 16% had 3 children as well as 10.7% had an ideal preference for 4 or 5. conclusion:  the study recommended an educational program to have optimal birth intervals and ideal number of children per family for the prevention of adverse prenatal outcomes.