Kate Middleton went into labor in the early hours of Monday morning, and going by expert opinion, the Duchess of Cambridge might deliver the royal baby by late afternoon or early evening local time, the Mirror reported.

Medical experts arrived at the estimated time frame based on the fact that the average length of labor for first-time mothers is 12 hours. The Daily Mail reported, on Monday morning, that Middleton was admitted to the hospital at 5:30 a.m. (12:30 a.m. EDT), which puts the earliest possible delivery time at 5:30 p.m.

However, the official announcement from Kensington Palace, stating Middleton was admitted to the Lindo Wing of St Mary’s Hospital in the early hours of Monday, was made only at 7.30 a.m., making it difficult to gauge the amount of time she has been in labor.

"With first baby, you usually dilate about a centimetre an hour and you've got to get from closed to 10 centimetres - which is fully dilated - so that's about 10 hours,” Patrick O’Brien, a spokesman for the Royal College of Obstetricians and Gynaecologists, told the Mirror.

"When you reach fully dilated usually you wait for an hour or so to allow the baby's head to come as low as possible, and then you push - and the pushing is about an hour to an hour and a half. So about 12 hours is the average, sometimes quicker, sometimes slower, but that's what you have to budget for.”

Hours after Middleton was admitted to the hospital, a source close to the royal family told the Daily Mail that Middleton is having a natural birth and that “things are progressing as normal.”

Her delivery is being overseen by a team of top medical professionals led by Marcus Setchell, the Queen’s former gynecologist. He is assisted by Alan Farthing, who is the Queen’s current gynecologist, The Scotsman reported.

Good wishes from across the country have been pouring in since news of Middleton being in labor broke early on Monday.

British Prime Minister David Cameron responded by saying it is a “very exciting occasion” and that the country is “hoping for the best,” while Justin Welby, the Archbishop of Canterbury, tweeted: “My thoughts and prayers are with Kate and the whole family on this enormously special day.”