بررسی نسبت افزایش فراوانی خانواده و برخی عوامل مرتبط با آن با استفاده از مدل رگرسیون لجستیک چندگانه در بوشهر

 Background and Aim:To assess of human force and population's programming at high level, is very important that we know rates and characteristics of population. Growth of population has direct relationship with fertility rate of women in community. To control of population and arrive to index of N.R.R.(Net reproduction rate) equal to one ,each family must be has one or tow children .Thus ,in families that they have more over tow children, we must be search about factors affected and attempt to reduce of population's growth , until arrive to a stationary population. Materials and Methods: The cross-sectional study upon 500 women that are married and have 45 years old and more in Bushehr. Tow-stage random sampling was used in this study. First, Bushehr divided into 23 hypothesis blocks of 1000 households and thus, 20 points from each of blocks were selected by chance. Also, from each of 20 pointes, 25 families were selected by chance. In this study, a questionnaire was used for collecting of data, that questioners were asked of chief of households. The data was analyzed with SPSS package version 13. To find relationship between variables together and with response variable , was used kendall's tau test and chi-square for trend test. The multiple-logistic regression was used to find factors affected on parity progression ratios. Results: In this study 181 persons(36.2%) of women had illiterate, 229 persons(45.8%) had primary education and 90 persons(18%) of them had high and more education .The age of the first marriage of 456 persons(91.2 %)  of women were under 25 years old and the age of the first pregnancy of 196(39.2 %) of them were under 20 years old. Probability of arrive to the first child in Bushehr was equal 0.98,and probability of arrive to second, thirst and fourth children was equal 0.92,0.81 and 0.72 respectively. This study shows that the factor like the age of the first marriage of women has a negative effect on PPR (parity progression ratio) from zero to one child, and the factors like the women's education and having a dead child have a positive effect on it. The results indicate that the factor like having a dead child has increasing effect on PPR from one to tow children, and the factors like the women's education, the age of the first pregnancy and marriage have a decreasing effect on it. In this research it is observed that having a dead child has a positive effect on PPR from tow to three children, and the factors like the age of the first pregnancy and marriage, education of women and their husbands have a negative effect on PPR from tow to three children. Also it is observed that sexually and having a dead child has increasing effect on PPR from three to four children, and the factors like, the women's education, job and education of husband , and the age of the first pregnancy of  women have decreasing effect on PPR from three to four children. Conclusion: The results indicate that probability of arrive to third and fourth children are high. Thus it is show the controlling of family planning in Bushehr dose not good carry out within families belong lately decades.