Choosing the sex of your baby is a process known as sex selection. This is becoming increasingly common for couples with two or three children of the same gender. There are methods you and your partner can do to make the gender of your offspring more proportionate. It's said that if you use a bicarbonate douche an hour before intercourse, and delay intercourse until late in the ovulation cycle, you can alter the normal ratio of boys to girls. The doctor can also assist in sex selection. The sex of the baby is determined exclusively by the sperm cells, which carry an X chromosome for a girl or a Y for a boy. Sperm cells having X-chromosomes are heavier and bulkier, and move slower. As a result, the faster, lighter sperm cells, the Y-chromosomes, can be separated by passing the sperm sample through a special sperm wash. This process separates the X-chromosomes from the Y's the sperm sample is then used by the simple process of insemination. Sex selection isn't an exact science and isn't always successful in correctly choosing the sex of the baby.