It is now possible to ascertain if a pregnant woman will deliver a boy or a girl as early as five weeks after conception thanks to a new blood test.
Scientists at Cheil General Hospital in Seoul, South Korea, found that various ratios of two enzymes, which can be extracted from a pregnant mother's blood, indicate the baby's gender as early as five or six weeks, the Daily Mail reported.
The team, led by Dr Hyun Mee Ryu, said knowing the sex early is important if the mother is a carrier of an X-chromosome gene that can cause a disease like muscular dystrophy or haemophilia.
Female foetuses are either free from the disease or are carriers, but a male has a 50 per cent chance of inheriting the disease and parents may choose to abort the pregnancy.
However, the team warned: "This method might promote the potential for sex selection. Therefore, there should be careful consideration about the use of this analytical tool in clinical situations."
Current tests in the UK cannot be performed until 11 weeks and carry a one to two per cent risks of miscarriage as they require a sample from the amniotic sac that protects the foetus.
Meanwhile ultrasounds do not reveal a baby's outward genitalia, and therefore the gender, until well into the second trimester, and even then they can often be read incorrectly.
Dr Hyu wrote in the January edition of The FASEB Journal that their test could "reduce the need for invasive procedures in pregnant women carrying an X-linked chromosomal abnormality and clarify inconclusive readings by ultrasound."
The researchers collected maternal plasma from 203 women at the Cheil General Hospital during the first trimester of their pregnancies between 2008 and 209.
They were able to faultlessly detect the gender of the baby from as early as five weeks by measuring the ratio of the amount of the enzymes DYS14 and GAPDH in the blood plasma.