Many parents want to know the sex of their unborn child

The kit, sold by DNA Worldwide for £189, is controversial. Critics claim it may prompt parents to abort if they are unhappy with the test result.

The company rejected these claims, saying the early results, obtained from a finger-prick of blood, allow parents more time to plan for their baby.

It says the test is 99% accurate and offers a refund for wrong predictions.

The concept of an early pregnancy sex test is not new - last year the UK's Institute of Child Health successfully trialled a similar "seven week" test.

But this was used for women at risk of having babies affected by disorders that usually only affect boys, such as Duchene muscular dystrophy.

This test is very dangerous. It would inevitably lead to babies being aborted simply for not being the 'required' sex

Michaela Aston of the pro-life charity LIFE

Currently, some hospitals will tell a couple the sex of their child, if they want, at their 20 week ultrasound scan.

But David Nicholson, director of DNA Worldwide, said parents are excited by the pregnancy and don't want to have wait until their 20-week scan to find out.

Once a woman has taken the test, she sends her sample directly to the company's laboratory for analysis and will receive the result in the post or can access it online using a protected password.

The test looks for DNA from the baby in the mother's blood. If it picks up a Y-chromosome, that means a baby boy can be "confidently" predicted.

If there is no Y-chromosome DNA, the company can state "with equal confidence" that the baby will be a girl, the company says.

Ethical concerns

Campaigners were worried about the possible ramifications.

Julia Millington of the Prolife Alliance said: "There is a real risk that some people would choose to abort babies of a certain gender."

Michaela Aston of the pro-life charity LIFE said: "This test is very dangerous. It would inevitably lead to babies being aborted simply for not being the 'required' sex."

She rejected the notion that the test would allow parents more time to plan for their baby's arrival, arguing that the needs of baby boys and girls were identical.

She was also concerned it would lead to some women in some countries being coerced into having abortions.

Mr Nicholson said surveys of the company's US customers, who have been able to buy the test since 2006, suggested these concerns were unfounded.

But he said he welcomed an open and wider debate on this topic.

He stressed that any couple wanting to find out the sex of their child for medical or genetic reasons should seek the help of a medical practitioner who could provide counselling - something not provided alongside the company's test.

The Royal College of Obstetricians and Gynaecologists believes sex selection for non-medical purposes is inappropriate.

A spokesman added: "Focus should remain firmly on the health and care of the mother and developing baby, rather than gender."