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It is common belief (superstition, knowledge?) among midwifes and obstetricians that there is an accumulation of births near full moon. This assumption is found world wide in different manners. At first the development of birth related superstition is pointed out. This is explained by the common obstetric helplessness until a century ago facing birth complications. This lead to an extreme level of perinatal mortality and morbidity both for mother and newborn. For at least to have the illusion of having control over the uncontrollable birth related superstition developed.
Scientific rejection of superstition is nearly impossible. So the aspect of moon phase dependency of birth rate was selected as there is comprehensive data from the perinatal survey of hesse to review this hypothesis.
Material and methods
With data from the perinatal survey of hesse covering the years from 1990 to 1998 including 526,225 birth the following questions were reviewed:
Is the distribution of birth rate dependant on moon phase?
Is there a change in birth rate on days with specific numeric properties?
Using VBA-Macro a “moon phase variable” was created which assigns a numeric value between 0 and <1 to all births describing the exact position within the lunar cycle. This variable was classified and tested for significance using chi square . Furthermore several time intervals were created around the exact times of full and new moon, first and last quarter. As the distribution of the precise moon phases over one day is very irregular and likewise the distribution of birth shows typical peaks and dips extensive adjustments were required. Within these time intervals birth rate was tested using c2 statistics.
As for the days with specific numeric features frequency of birth was also tested using chi square . Likewise there was the necessity of adjustments as there exists a distinct effect of day of week and of holidays on the birth rate.
To differentiate between natural and medically induced child birth a corresponding variable was created.
For the classified „moon phase variable“ as well as for all tested time intervals around the moon phases no significant divergence could be verified. This applied for all unselected births as well as for natural births.
For none of the tested days with specific numeric features a change in frequency of births could be detected. This applied for all unselected births as well as for natural births.
No evidence was found for the wide spread belief that birth rate will rise on full moon. On the other hand lunar influence has been verified on many biological processes. Further on changes in seasonal and circadian rhythms of birth frequency have been found in historic time. So it is presumed that if at all a possible minimal lunar influence is no longer detectable under modern lifestyle.