If you wish to know your baby's gender there is a new blood test for foetal DNA. 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 pregnancy. 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 ultrasound to determine sex by a month. The reason why determining sex can be important is for detecting gender-related genetic 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 haemophilia.
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.
