Is voluntary abortion a seasonal disorder of mood?

BACKGROUND: Depressive mood and suicides are more frequent in women seeking voluntary abortion and occur in a seasonal rhythmic fashion. Whether voluntary abortion shows a similar seasonal rhythm was investigated in this study. METHODS: A 4-year analysis was performed on the database of the National Institute of Statistics (ISTAT) (508 130 abortions) and on the medical records of our institute (3463 abortions). The ratio of voluntary abortions to the number of vital pregnancies (terminated with birth and voluntary abortion) present at the third month of gestation (8-12 weeks) was evaluated. Analyses were carried out by the periodogram method. RESULTS: The rate of voluntary abortions showed a seasonal rhythm with an amplitude of 6.1-6.7% and peaked in May (+/- 38 days). The national frequency of female suicides, obtained from the same ISTAT database, showed a similar rhythm, with an amplitude of 11.1% and maximal rate in June (+/- 37 days). CONCLUSIONS: The present data show a seasonal rhythm in the rate of voluntary abortion, which is almost identical to that of female suicides. This link suggests common provocative mechanisms and may indicate common preventative measures.