PINK OR BLUE?
Have you heard an old wives’ tale about how to ensure you have a boy or a girl? For a girl, some say you need to have sex during full moon. What does science say? We’re born with 23 sets of chromosomes, one of these sets being the sex chromosomes. Women have two X chromosomes and men an X and a Y chromosome. Sperm can carry the X or the Y chromosome, while an egg only contains an X chromosome. When an X chromosome fertilises the egg, it’s a girl. Otherwise, it’s a boy, explains geneticist Prof. Louise Warnich, dean of sciences at the University of Stellenbosch. The ejaculate has millions of sperm cells, which makes it difficult to predict which one will fertilise the egg. X- and Y-chromosome sperm cells have an equal chance, which is why scientists think the sex of the foetus is the luck of the draw.
Research on artificial insemination shows that the glucose level in women plays a part: higher glucose levels encourage the growth and development of male embryos. Fewer boys seem to be born in countries with lower average kilojoule consumption, and glucose levels are lowered by skipping breakfast. Women’s testosterone levels are generally a 10th of those of men, and higher levels can lead to boy births. More boys than girls are believed to be born during times of war, since stress increases testosterone.
The American biologist Dr Landrum Shettles reckons the acid level of the insemination process and -environment plays a part. The Y-sperm cells prefer a more alkaline environment. For a girl, you can rinse yourself with vinegar and water before sex. Avoid an orgasm, which creates a more alkaline environment. Boy sperms are apparently faster than girl sperms, but they don’t have as much staying power. Having sex every 48 hours during ovulation improves the chances of a Y sperm reaching the egg first. Sex up to three days before ovulation could ensure that X sperms reach the egg because they live longer. Caffeine for him before sex gives the Y-sperm cells the va-va-voom they need to get to the egg first. With in-vitro fertilisation, you’re 100 percent in control, because the sex of the embryo can be determined beforehand.