Kate Middleton went into the labor early Monday morning at the height of anticipation for the royal baby, and some are guessing that the moon had something to do with it.
As the Duke and Duchess of Cambridge prepare for the imminent arrival of their first child, some royal fans are already speculating over the baby's birthday.
Long-held beliefs and old wives tales about childbirth are coming into play due to Middleton's labor having started during a full moon.
One report indicated that the Duchess' labor pains were not only the result of the full moon, but because of thunderstorms in the London area, according to the U.K.'s Daily Star.
"It's always sort of been an old wives tale saying that the full moon brings women into labor," said Mervi Jokinen of the Royal College of Midwives.
"Midwives usually do say 'I'm on call. It's a full moon. I'll be busy tonight,'" she added.
Some believe that the moon's gravitational pull affects the amniotic fluid just as it does seawater.
"The idea is that because the baby is surrounded by water, the time of the full moon and the high tide causes the waters to break," said Jokinen. "But there's not enough scientific evidence to show it's proven."
Meanwhile, the Duke and Duchess of Cambridge arrived to the Lindo Wing at London's St. Mary's Hospital at 6 a.m. (1 a.m. EST) on Monday, according to a statement from the Palace.
"Her Royal Highness The Duchess of Cambridge has been admitted this morning to St. Mary's Hospital, Paddington, London in the early stages of labour," said the statement.
"The Duchess travelled by car from Kensington Palace to the Lindo Wing at St. Mary's Hospital with The Duke of Cambridge," the palace added.
The husband and wife entered the hospital through a rear entrance, according to Us Weekly. As for Middleton's labor, "things are progressing normally," an insider said.
Once the baby arrives, the gender, weight and time of birth will be revealed in a public declaration posted to a wooden easel right behind the gates of Buckingham Palace- a longstanding tradition.
However, the child's name may not be immediately released.