Scientists from Yale University looked at birth records for the ten years between 1996 and 2006. They showed that, compared to the days around Halloween, there was a 5.3% decrease in spontaneous births and a 16.9% decrease in cesarean births for Halloween day itself.
The scientists believe that this may be due to negative associations of "witches and death" with the festival. They also looked at birth rates in and around Valentine's Day for the same period and noticed a significant 12% increase in cesarean births and a 3.6% increase in spontaneous births.
The scientists noted the positive associations of "flowers and love" with Valentine's Day.
|Effect of Halloween on timing of birth (Source: Levy et al., 2011)|
The researchers conclude that the term "spontaneous births" is erroneous and it appears that pregnant women can "expedite or delay spontaneous births, within a limited time frame, in response to cultural representations".
It seems that the cupids and cherubs of Valentine's Day is a much more appealing prospect for an expectant mother rather than the ghouls and skeletons of this time of year.
Levy et al. (2011) Influence of Valentine's Day and Halloween on Birth Timing. Social Science and Medicine 73(8): 1246-1248. LINK