Tui mới tìm trong web nè, không biết có đúng không :
Some may scoff, but others swear by these simple selection methods to help couples conceive the baby of their preferred sex - without resorting to the geneticists?
The Shettles method
This method of gender selection has been around since the 1960s. Dr Shettles recommends methods of gender selection most upheld by scientific evidence and without costly or controversial medical procedures.
The basic premise is that men produce two types of sperm, the X (female) and Y (male). According to Dr Shettles' studies, the male (Y) sperm are smaller and weaker but faster than the female (X) sperm, which are bigger, stronger and slower. Understanding this information helps in manipulating the sex of your child.
The right time
The most important factor in gender selection is the timing of intercourse during the monthly cycle, so the woman must know her cycle (ovulation predictor kits are available at most pharmacies). The Shettles' method believes that the closer to ovulation you have sex the more likely it is that you will have a boy. However, if you have sex two or three days prior to the egg being released, you have a better chance of having a girl. Basically, if you have intercourse right at or near ovulation then the Y sperm will make it to the egg quickly and you have a boy, whereas if the sperm is released two or three days before the egg, the Y sperm will die off and there will be more X sperm left waiting for the egg to appear and fertilisation will most likely result in a girl.
Vaginal pH
The pH of a woman's vagina is also very important. An acidic environment favours girls, since it will kill the weaker male sperm first and leave a greater number of X sperm to fertilise the egg. So, if you are trying for a boy, a good time for intercourse is when the vaginal balance changes to alkaline - on the day you ovulate - otherwise the male sperm will either slow down or die in an acidic environment.
Sexual position
Position of intercourse and depth of penetration are also important, partly because of pH. The closer to the entrance of the vagina, the more acidic the woman's tract is. Deep penetration places the sperm closer to the egg and gives the faster male sperm a head start. Shettles recommends the missionary position for girls and deeper penetration positions such as rear entry (doggy-style) for boys.
Sperm count
Obviously a low sperm count to begin with doesn't favour either sex, but a high sperm count favours boys. Shettles recommends that when trying for a boy, the man wear loose underwear because the testicles need cooler temperatures for sperm to survive and thus the weaker Y (male) sperm will benefit from this more than the stronger X (female) sperm. For a girl, it is suggested that the man have a hot bath immediately before intercourse to give the X (female) sperm an advantage (by killing off the weaker male sperm).
Food for thought
It is thought that minerals in your diet affect the metabolism and environment of the egg and therefore make it more attractive to sperm of one particular sex. If you want a boy, eat plenty of potassium-rich foods such as meat, bananas, apricots and celery. If you want a girl, lots of magnesium-rich foods such as nuts, soya beans and leafy green vegetables should do the trick.
Old wives tales
For a boy:
Allow your partner to seduce you into sex first
Eat red meat and salty snacks
Have intercourse at night
Have intercourse on the odd days of the month
Have intercourse during a quarter moon
For a girl
Seduce your partner
Eat fish and vegetables and have a high-dairy diet
Have intercourse in the afternoon
Have intercourse on the even days of the month
Have intercourse during a full moon
http://www.ivillage.co.uk/pregnancya...534749,00.html
http://preconception.com/resources/a.../boyorgirl.htm
___ __ \_____ ___ ____(_)_____ /
__ / / / __ `/_ | / /_ /_ __ /
_ /_/ // /_/ /__ |/ /_ / / /_/ /
/_____/ \__,_/ _____/ /_/ \__,_/