Lucky days to be born on

As explained here, each day of the Rokuyo calendar is associated with luck. However, the evidence of any Rokuyo effect on birth delivery days is thin and unlikely to feature much in the parents' decision making. Only a fool would risk messing about with nature by relying on superstition; it goes against natural human behaviour to put one's offspring at risk.

That said, there's a superstition in Japan called 丙午 Hinoe-Uma ('Fire Horse') and there's evidence that Hinoe-Uma heralded the end of the baby boom. And get this - the Hinoe-Uma is a calendar event that occurs every 60 years. (more...)

To trust Rokuyo (an ancient custom with a dodgy reputation) would be to say that Rokuyo had miraculous powers, and it is commonly accepted that miracles are the working of a divine power. If you feel that Rokuyo or astrology is divine, then you are missing out on something infinitely more wonderful.

Until recently, deciding on which day a baby is born has not been possible. But with the advent of induced labour, there is a slight tendency for some parents to request delaying birth by a day or two, or hastening it, to avoid Butsumetsu or to coincide with Taian. Doctors naturally discourage such approaches.

This happens not only in Japan but all across Asia. In Taiwan for example, a study in 2003 showed increases in deliveries on auspicious days and decreases on inauspicious days according to the Chinese lunar calendar. However, in the vast majority of cases the joy of having a baby, plus the emotional strain, don't leave much time for parents to consider Rokuyo very much, if at all.

Rather than the parents deciding the delivery date, their doctor, who is ever mindful of the necessity to have happy parents rear a child, will always advise that the best day is the day decided by the baby. With the advances in medicine it may be possible in the future to have such designer births with no risk to the child. Whether this will happen before the Rokuyo system fades from Japanese culture remains to be seen.

Having said all that, making such decisions may be a waste of time. In 2011 researchers at Yale School of Public Health examined 1.8 million US birth certificates over an 11-year period and found that birth rates dropped by 11% on spooky Halloween, when compared with one week on either side of the date. This applied to both 'natural' and induced births. They also noted a 3.6% increase in spontaneous births and a 12.1% increase in caesarean births on Valentine's Day. The study suggested that a psychological influence over hormonal activity may be at work.