Some unexpected results in time distribution analysis of spontaneous deliveries.
OBJECTIVE
To study time distribution of spontaneous deliveries.


METHODS
A retrospective analysis of 1,791 spontaneous deliveries over a 4-year period (1993-1996) was made at the department of Obstetrics and Gynaecology, Civil Hospital, Fano, Italy. Circular statistics techniques (maximization of mean vector length) were used.


RESULTS
Some unexpected infradian disuniformities (with 60- and 90-hour periods) were observed. Moreover, a correlation between the distribution of spontaneous deliveries and the lunar phases was found.


CONCLUSIONS
In this study, some unexpected infradian disuniformities were found. However, no biological explanations appear to be reasonable in light of current knowledge, so the interpretation of these results remains an open question.
Institute of Biomathematics, Urbino University, Urbino, Italy.
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Cancelli
D036861:Delivery, Obstetric / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D010507:Periodicity; D011247:Pregnancy; D012189:Retrospective Studies