Doctors and nurses who work in the delivery room should not fret during the next full moon: a new study has found no evidence to support the common belief that births and delivery complications spike during full moons.

Some people believe that maternity wards are more crowded during certain lunar phases, especially during a full moon, but the notion didn’t hold up under scrutiny.

Dr. Jill M. Arliss, of Mountain Area Health Education Center in Asheville, North Carolina, did not find any connection between the lunar cycle and births in a review of more than 500,000 births in North Carolina.

“You can look at your calendar for the full moon closest to your due date and still not have any better idea about when your baby will be born than if you picked the new moon, the first quarter, the last quarter or any day in-between,” said co-author Shelley L. Galvin.

“We really don’t know what starts the process of labor, but we do know that whatever it is, it probably has nothing to do with the phases of the moon,” Galvin said.

The results of previous scientific studies of a possible lunar-labor connection have been mixed. Some studies have shown a relationship between the lunar cycle and an increase in deliveries, but the studies have differed on which moon phase produced the most births.

The North Carolina researchers compared the frequency of births and birth complications across the eight phases of the moon, and report the results in the American Journal of Obstetrics and Gynecology.

As well as finding no significant association between the frequency of births and the phases of the moon, the researchers also saw that the frequency of labor and delivery complications did not differ significantly from phase to phase.

Galvin said that other researchers will argue that she and her colleagues should have examined the birth data in different ways, such as by looking at the start of labor rather than the end of labor. Studies that look at the data in other ways may reveal a pattern that fits in with the phases of the moon, she said.

“But we tried to find the patterns that other researchers had found, and we still couldn’t find any predictable pattern,” Galvin said.

“So while it may be fun to consider the full moon closest to your due date as the future ‘birthday’ for your baby, you’d have as good a chance of being right as throwing a dart at your calendar,” Galvin said.

SOURCE: American Journal of Obstetrics and Gynecology, May 2005.