Kate Middleton is in labour - at last the day we've all been waiting for has arrived.
The Duchess of Cambridge was taken to her private birthing suite, the Lindo Wing adjoined to St Mary's Hospital in London, just before 6am - so what happens now?
According to her birth plan, Kate plans to give birth naturally, as opposed to booking in for an elective caesarean as other mums in the public eye often choose. And the waiting world is on tenterhooks as the baby could arrive at any time over the next 24 hours.
Many women experience 'fake' contractions in the week or two before labour actually happens, known as 'Braxton Hicks'. But we reckon Clarence House has probably checked that this is the real thing before alerting the world media.
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In fact it's likely that Kate is already some way into her first stage of labour, as this lasts an average 12 to 14 hours for the first baby and the early part is usually spent at home. The second stage of labour lasts for around one to two hours and the final stage can be anywhere between five minutes and an hour - so our money's on a birth announcement this afternoon.
The first stage of labour is when the uterus and cervix open, felt by the mum-to-be as contractions, which increase in frequency and strength. The second is when the baby moves down into the birth canal, which is when the pushing we've all seen on TV birth scenes begins and the third stage is when the afterbirth is removed, beginning after the baby's birth.
Kate is thought to have planned a hypnobirth, which is designed to help women get through the pain of labour naturally. This involves breathing techniques to encourage calm.
Clarence House has also said that dad-to-be Prince William, like his father before him, will be at his wife's side for the birth. He will also be the one to telephone the Queen to give her the news when the baby arrives. The Middletons are expected to arrive at the hospital but the royal family will not.
Labour for first babies tends to be longer than subsequent births so it could be hours before the all important details - the weight, sex and disposition of the baby - are announced on a scroll in front of Buckingham Palace.
Labour is one of the most physically demanding things women will do in their entire lives, with it often compared to a marathon. If she doe find the pain difficult, she may be offered an epidural (a pain-killing injection administered into the spine), or gas and air.
Should Kate or the baby encounter any difficulties, the Lindo wing is attached to St Mary's hospital, where an emergency caesarean would be carried out.
However, as Kate is young, fit and healthy, it's expected she will have a natural birth - considered by experts to be the best option for both mum and baby. Her choice not to plan an elective caesarean has already been praised as an encourage to other women to follow suit, despite the fact that the NHS now offers women the choice.
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Natural birth usually takes less time to recover from than a caesarean, which is major surgery, and moving through the birth canal helps the baby's lungs expel any amniotic fluid so it can breathe more easily.
If the baby is born today it will be under the star sign Cancer - like its grandma Diana. But if it's tomorrow, it will be Leo perhaps suggesting a totally different personality.
For news of the birth as it happens, keep an eye on our Royal Baby Live Blog.