Fox News Weather Center

Could a Full Moon or Pressure Changes Have Induced Middleton's Labor?

As Catherine, Duchess of Cambridge, prepares to give birth at St. Mary's Hospital in London, we have to ask: is it possible a change in barometric pressure has helped to induce her labor?

People have latched on to many long-held, weather-related wives' tales over the years. If cows are lying down in a pasture, rain is on the way. If a groundhog sees his shadow on Feb. 2, six more weeks of winter are in store.

And, of course, if barometric pressure changes, labor may be induced in pregnant British royalty.

Okay, we added that last bit, but studies do support that changes in pressure can induce labor.

According to the U.S. National Library of Medicine and the National Institutes of Health, "In the field of obstetrics and gynecology, several events have been empirically shown to be related to the weather."

In a study conducted by the Department of Obstetrics and Gynecology at the Tokyo Medical University, results showed that on days with a larger change in barometric pressure, regardless of whether it was increasing or decreasing, the number of deliveries increased.

"There is no question in my mind that when there is certain combinations of pressure changes, or a full moon, or storms, or snow -- I think it's mostly change in barometric pressure -- my patients go into labor," Jacqueline Worth, MD at Village Obstetrics in New York City, said.

"We absolutely have observed huge variations with weather."

Though Worth has not seen it supported in literature, she is certain it happens, noting the similar associations that have been made with migraines, heart attacks and other physiological conditions.

"The pressure in London has fallen by about 4 mb from yesterday to today," Meteorologist Eric Leister said. " It's a notable drop, but a small one. The pressure is capable of dropping much more than that in 24 hours, of even just a couple of hours," he said.

As the moon neared its full stage over the weekend, Worth took notice. Three babies were delivered at her practice over the weekend.

"It doesn't matter which direction [the pressure] changes in," Worth said. "All I know is that when those things happen I pack my bags and get ready to work."

Coincidence or not, as Catherine and the world await the delivery of the next royal baby, the night of July 22 will usher in a full moon.