trends in the human sex odds at birth in europe and the chernobyl nuclear power plant accident to investigate trends in the sex odds before and after the chernobyl accident genderspecific annual birth statistics were obtained from the czech republic denmark finland germany hungary norway poland and sweden between 1982 and 1992 for parts of germany annual birth statistics and fallout measurements after chernobyl are available at the district level trend models allowing for discontinuities of the male birth proportions are suggested superimposed on a downward trend in male proportions there was a jump in 1987 with a sex odds ratio of 10047 95confidence interval 1001310081 p00061 a positive association of the male proportion in germany between 1986 and 1991 with radioactive exposure at the district level is reflected by a sex odds ratio of 10145 per msva 1002110271 p00218 these findings suggest a possible longterm chronic influence of the chernobyl nuclear power plant accident on the human sex odds at birth in several european countries