01/05/2015 06:01 BST | Updated 01/05/2015 06:59 BST

The Duchess Of Cambridge Advised To Have Sex To Bring On The Birth Of The Royal Baby

The Duchess of Cambridge is believed to have tried swimming to bring on the birth of the royal baby, but that isn't the only labour inducing technique she and Wills may be trying behind closed doors.

Kate is now believed to be several days overdue, and as anyone who has been in her position will know, it can be tempting to try out many an old wives' tale to hurry things along - such as eating spicy curries, drinking raspberry leaf tea or... having sex.

duchess of cambridge

"There's nothing wrong with doing any of these things but there is no evidence to back them up," said Elizabeth Duff, senior policy adviser to pregnancy charity NCT.

"Having a curry is a good idea though as women will need all the strength they can get ahead of going into labour, when it is unlikely they will eat much."

However, TV doctor Hilary Jones disagrees with Duff about the lack of evidence to support the idea that sex can bring on labour.

Speaking on Good Morning Britain Hilary said: "The other thing I should mention at the risk of going to the Tower is sex and monarchy in the same sentence,

"If any woman wanted to, at that stage in pregnancy, it does actually help because the man delivers prostaglandins which are the same sort of hormones used to induce birth.

"Is that alright? It's just a medical fact. Let's not beat around the bush here."


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When does a pregnant woman become overdue?

Working out a pregnant woman's due date is not an exact science. The traditional method was devised back in 1850, by German obstetrician Franz Karl Naegele.

His formula, known as Naegele's Rule, calculates the date by adding nine months and seven days to the first day of the woman's last period.

The result is approximately 280 days or 40 weeks from the start of her last period, but the method is flawed as it makes several assumptions including that all women ovulate every 28 days and that every calendar month has the same number of days.

Also the length of a pregnancy can vary. A baby is considered full-term at 37 weeks and most women will go into labour between 38 and 42 weeks.

A more scientific technique for working out a pregnant woman's due date is by using an ultrasound scan. Women are offered at least two ultrasound scans on the NHS, at eight to 14 weeks and 18 to 21 weeks.

It is at the first scan that the sonographer will be able to give the woman an estimation of when the baby is due, based on its measurements.

Obviously, many women will also have a good idea of when they conceived, based on when they had sex.

What happens if a woman becomes overdue?

At around the 41st week, women will be able to talk to their midwife about what they want to do. They can be induced by having a membrane sweep, which involves an internal examination that stimulates the cervix. Contractions can also be started by inserting a tablet (or pessary).

Around one in five labours are induced in the UK and Elizabeth Duff, senior policy adviser to pregnancy charity NCT, said it is very much down to the woman to decide.

"Some are very keen to have as spontaneous and normal a labour as possible," she said. "The woman may say 'let's just wait at least a week and carry on being active and doing normal things'.

"Other women might have reasons to make the baby hurry up like their partner is going away, for instance, while some woman feel very, very heavy and can't rest as they can't get comfortable at night.

"Some women will feel just have an intuitive feeling, like it doesn't feel right yet."

Most women will have given birth spontaneously by 42 weeks, but if it reaches this time they will be offered increased monitoring and a caesarean section may be carried out.

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