How to determine the sex of your child

2nd week

A research team from the prenatal genetic diagnostics department of the Tel Aviv Medical Centre found that a woman’s hCG concentration is about 19 percent higher when she’s carrying a girl than it is when her baby is a boy. The researchers collected blood from 347 women. The hCG tests carried out from 1 to 3 times between days 14 and 20 of pregnancy showed that the levels of maternal serum hCG were 18,5% higher, within just 16 days of conception, among women who gave birth to girls.
The study was overseen by Dr Yuval Yaron who said that even though the research results are quite accurate, a prediction with high probability is too small. According to the scientists, some other markers are still needed to predict it for sure.
Tests measuring the hCG level have been long used as the principle of take-home pregnancy tests. This test is also useful to detect an extrauterine pregnancy and other dangerous malformations and diseases, for example, it identifies fetuses with Down’s syndrome. 

6th week

A British company DNA Worldwide has invented a Pink or Blue Early Gender Test that claims it can predict the baby’s sex as early as at the 6th week of pregnancy. The test has become available on-line, and parents all over the world, except for India and China where gender selection is a big concern, can buy it now. In the U.S. the test has been available, also on-line, since last year.
The test analyses the embryo’s DNA cells contained in the mother’s blood. If the test indicates the Y chromosome presence, that means that it’s a boy that the mother is carrying. The parents who have ordered a test receive a specialized DNA collection card. The blood is collected though a finger prick (in the form of a blood spot on the card) and then returned to the laboratory for the analysis. The company promises to predict the gender of the child within 5-6 days. The test developers claim that the test is 98% accurate if everything was done according to the instruction. In case of failure, DNA Worldwide promises a refund for wrong predictions. Out of all the tests sold on the web since April, the company has offered a refund only to one woman.
Nevertheless, the new test raises certain concerns. Specialists doubt it’s accuracy saying that the earlier stage of pregnancy is, the fewer DNA cells of the embryo are contained in the mother’s blood. Thus, a 100% accuracy result can be obtained at the 20th week of pregnancy only. Still, there is another test – amniocentesis -  that defines the baby’s sex with a high accuracy at the 11th week already. `
Critics claim it may prompt parents to abort if they are unhappy with the test result.
Whatever people might say, researchers never stop to work. In the nearest future we may have tests able to indicate fetuses with serious genetic diseases, such as Down’s syndrome, at early stages of pregnancy.