CRONOBIOLOGIC ANALYSIS OF ABORTIONS IN 2 RELATED POPULATIONS OF TEENAGER GIRLS DURING 2 DECADES

Study Objective: To identify and compare the time dynamics of artifici al abortions in two (Czech and Slovak) ethnically, historically and so cially closely related populations. Design: Data have been taken separ ately for 12-15 and 16-18 year age girls from official exhaustive stat istical sources and processed by advanced procedures of time series an alysis. Setting: Czech and Slovak Republics. Participants: All girls o f the given age. Interventions: Legislative liberalization of abortion s 1987. Main Outcome Measures: Estimated starting values of relative n umbers of abortions by 1971, increasing linear trends, period lengths of fluctuation, coefficients of determination and those of cross-corre lation. Level of significance alpha = 0.05. Results: The Czech figures are significantly higher than the Slovak. Thus, estimated abortion pe rcentage (from pregnancies) for 1971 was for younger Czech girls 53%, and for those from Slovakia 29%. All estimated trends were increasing significantly in all cases for the Czech population (by 1.5% per year in the younger group) and in one case for Slovakia. The estimated peri od lengths were usually 10-12 years. Czech and Slovak data display sig nificant positive mutual cross-correlation, the delay being 1-3 years in Slovak girls. Surprisingly, all data significantly cross-correlate with the geomagnetic index value Ap, acting as lead-lag, with 3-6-year delay for abortions. Conclusions: Despite living in the same federal state - the former Czechoslovak Republic, both Czech and Slovak popula tions do differ in starting values and general trends of abortions in teenagers. This can be due to historical, racial and religious peculia rities as well as a more advanced process of industrialization in the western part - the Czech Republic. The latter hypothesis is corroborat ed by strong dynamism of changes and by the time delay in Slovakia. Th e periodicity exhibits a frequency resembling that known for solar mot ion round barycenter of solar system, for sunspots and geomagnetism.