Interest in gender selection has a long history dating back to ancient cultures. Methods have varied from herbal concoctions to different sexual positions, while Mother Nature has tipped the odds slightly in favour of boys with 1050 boys being born to every 1000 girls.
As the methods vary, so do the motivations. Modern parents often long for the perfect pigeon pair while in other cultures, status and economic usefulness determine the desired gender. In some cases parents wish to avoid a gender-related genetic disorder or want to determine the birth order of their boys and girls.
Low-tech sex selection methods are cheap and easy, far from foolproof and really more fun than scientific. They won’t hurt and there is about a 50% chance of success.
The most accurate sex-selection methods are the most expensive, highly invasive and involve fertility treatments. Some are only legal for medical reasons and they raise hot debate on the ethics of gender selection.
Here's a break-down of the more popular methods of gender selection:
The Jonas Method
Dr Eugen Jonas of the Centre Jonas International Research Corp in Australia claims that under certain circumstances the bio-chemical endometrial environment is subject to certain periodic variations and that these lead to sedimentation of sperm.
His method teaches that there are some days in a woman’s fertility cycle during which she can conceive a boy only and days when only a girl can be conceived.
To find out more about the Dr Eugen Jonas Method for Natural Conception Control, visit his website.
The Shettles Method
The Shettles Method has all to do with when you ovulate, the sex position, timing and pH balance, as explained in How to Choose the Sex of your Baby by Dr Landrum B Shettles and David M. Rorvik (1989).
Y-chromosome sperm (male) are smaller and weaker but faster, while X-sperm (female) are bigger and stronger but slower. According to this method, the closer to ovulation you have sex, the better the chance of having a boy as the Y-sperm will probably reach the egg first. But if you have sex a few days before ovulation, only the stronger X-sperm will survive to fertilise the egg upon ovulation.
The position of intercourse and depth of penetration is important in this method, as is the acidity/alkalinity of the women’s reproductive tract. Thus, if penetration is deep, where it’s more alkaline, it is said to be conducive to conceiving boys. Position-wise this means go missionary position for girls, rear-entry for boys.
Orgasm for a woman makes the vagina alkaline and Shettles claims this therefore favours boys. To up the chances of a boy, he suggests you need heaps of sperm so men must have sex only on ovulation day for a boy, while the woman must have a hot bath, plus a cup of coffee.
Research shows a 50/50 success rate.
The Whelan Method
Dr Elizabeth M. Whelan, president of the American Council on Science and Health, contradicts the Shettles Method, saying that biochemical changes that favour boys occur earlier in a woman’s cycle so if you want a boy, have sex 4 or 5 days before ovulation. To learn more, read her book Boy or Girl? (Macmillan).
The Ericsson Method
A technique pioneered by Ronald Ericsson in the 70s claims to be around 75% successful, but fertility doctors say it’s no higher than 50%.
The method aims to separate fast-swimming boy sperm (Y chromosome) from the slow girl sperm (X chromosome) in a test tube. The boy sperm swim down faster and reach the bottom, while the girl sperm hang around the top. The sperm are then separated and introduced by artificial insemination.
Check out the Ericsson website on www.childselect.com.
Flow cytometry (pre-conception sex selection) or MicroSort technology tags X and Y chromosome sperm with different fluorescent dyes so they can be segregated into different batches and then used in either artificial or in-vitro fertilisation (IVF).
Previously used successfully in animal husbandry, it’s now being adapted for human use. The technology is relatively new and the method doesn’t guarantee success.
For more information, visit www.microsort.com.
Pre-implantation genetic diagnosis (PGD)
Pre-implantation genetic diagnosis (PGD) or embryo selection techniques evolved from IVF and artificial insemination. Fertility drugs stimulate your ovaries to produce several eggs for fertilisation, so that multiple embryos can be created. The embryos are tested to determine the sex chromosome and only those of the desired gender are implanted.
The chance of pregnancy is just 30% but among those, the chance of conceiving the preferred sex is 100%. This is not a cheap option and multiple births are common.