Objective: Overall objective is to detect changes in reproductive health of women due to changes in the system of social and health care. The particular objective of this part of the study (part IV) is to identify the changes in the relationship of decreasing number of induced abortions and increased use of contraception in 1997 compared to 1993. Design: Retrospective comparative epidemiological study. Setting: Institute for the Care of Mother and Child, Praha 4 - Podolí. Methods: Input data for the comparison of number of induced abortions and extent of contracepti- ve use came from the results of two previous parts of the study (parts II and III). The relationship of contraceptive use and induced abortions was analyzed with regard to possible effect of concur- rent development of selected social-demographic factors. Results: The highest decrease of absolute number of induced abortions, together with higher- than-average decrease of absolute number of women not using one of three effective methods of contraception, was among married women, women with two children and women with secondary education without exam. On the opposite, the highest relative decrease of women not using one of the three contraceptive methods was among women 20-24 year of age, women without children and women with university education, although such change was not reflected in relative decrea- se of number of induced abortions in these groups. Furthemore, their relative decrease was even smaller than the national average. Similarly, the highest relative decrease of number of induced abortions among divorced women and women 25-29 year of age was linked with less-than-average decrease of number of women not using one of three effective methods of contraception. Conclusions: Different values of changing relationship of contraception and induced abortions in relation to analyzed social-demographic factors during period of observation document the influ- ence of these factors without dispute. Due to complex influence of these factors on the relation- ship of contraception and induced abortions, the particular contribution of each of them is difficult to asses during simple analysis one-by-one.

        Key words: epidemiology, induced abortion, contraception, social-demographic factors