If you wish to know your baby's gender there is a new bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. test for foetal DNAThe building blocks of the genes in almost all living organisms - spelt out in full as deoxyribonucleic acid.. The tests have been available for some time, but until recently there has been concern over their accuracy. Following a study of over 6,000 test results the test has been found to be 98% accurate - providing it was used after the seventh week of pregnancythe period from conception to birth. Earlier testing than this made the test unreliable. There are other tests that use urine as the preferred sample, but these appeared to be unreliable altogether.
The seven week period is important as this beats the ability of ultrasoundA diagnostic method in which very high frequency sound waves are passed into the body and the reflective echoes analysed to build a picture of the internal organs – or of the foetus in the uterus. to determine sex by a month. The reason why determining sex can be important is for detecting gender-related geneticRelating to the genes, the basic units of genetic material. disorders, and the new test reduces the amount of time needed to wait. For example, Great Ormond Street Hospital uses the test for detecting male babies that could have haemophiliaA hereditary disorder that causes very slow clotting of the blood, due to deficiency of a coagulation factor (either Factor VIII or Factor IX)..
The blood tests had a sensitivity of 95% and specificity of 98.6%. So, if the test was used by 100 couples, it might be wrong on two occasions. Therefore, despite the good indication a confirmation test is still required.