It is rumored that the PH value has an effect on the birth of boys. And many couples who want to have a boy want to try to create an alkaline environment by rinsing the vagina with 2% or 2. 5% sodium bicarbonate solution before intercourse; couples who want to have a girl want to make the acidic environment bigger by rinsing the vagina with the appropriate concentration of vinegar or 1% sodium lactate solution before intercourse to increase the chances of having a girl. These statements, although they seem to have some truth, the human body is a complex living organism and the real determinants are not yet determined. Current medical research suggests that the real determinant of a male child is a gene called testicular determinant factor (TDF), which means that the sex of a fetus is determined by the TDF gene. Embryos containing TDF will develop as males and those without the TDF gene will develop as females. However, the sex determinants are still not fully understood so far and need to be further studied. Some fathers and mothers-to-be use vaginal irrigation to change the pH of the vagina in order to have a baby of the desired sex, which not only does not result in an ideal baby, but also has the opposite effect. This can cause vaginitis and pelvic inflammatory disease in the pregnant mother and even damage the sperm, causing malformations in the fetal baby. Some research results show that if the husband’s semen is weakly alkaline, the wife will have more boys; if it is weakly acidic, the wife will have more girls; and if it is neutral, the chances of having boys and girls are equal. Because if the body accumulates more acidic substances, can make the birth of boys Y sperm than X sperm vitality lost more and faster, in this case the children born will rarely have male. Researchers point out that husbands who want to have a boy should stop intense exercise and reduce energy consumption to keep body fluids alkaline. In addition, daily intake of alkaline foods, such as fresh vegetables and fruits should be increased.