People will debate the ethical issues of gender selection (aka 'sex selection') for years to come, but there is no stopping the fact that it is now possible. If you have decided that it's important for your next baby to be a boy or a girl, what options do you really have?

A quick round of web surfing will reveal that there are many methods of gender selection available, from those based on ancient traditions to those based on the most recent technologies. Some approaches will cost you nothing, others will set you back several thousand dollars.

Do any of these methods really work? To a certain extent, when it comes to gender selection, you get what you pay for, but for most people with an interest in increasing their chances of having a baby of one sex or the other, a simple fertility monitor may be the most practical tool.

Ancient Arts

According to the Ancient Chinese Birth Chart, said to have been unearthed after spending 700 years in a Beijing tomb, simply knowing the age of the mother is sufficient to tell you which month you are most likely to have a baby of the gender of your choice. It should be so easy. Maybe if the Chinese calendar worked, there would not have been so many girl abortions in China.

Then there is the ubiquitous Dr. Jonas, whose many websites offer to prepare a personalized chart based on a woman's birthdate and previous pregnancies. Dr. Jonas claims to have discovered a second fertility cycle operating in women, independent of the 28-day menstrual cycle, and that 85% of all pregnancies actually result from this second cycle. Jonas claims to have scientific validation for his method, but clients report that the online services provide a glorified astrological chart. 99% reliable? According to the Skeptic's Dictionary, "How could one doubt the word of a man who dedicated his method of birth control to the Virgin Mary... when he read an ancient Assyrian/Babylonian fragment that stated: 'A woman is fertile according to the moon'."

True Biotech

If you are determined to have a baby of one sex or the other, technology can surely help. A number of fertility clinics offer sperm sorting using the MicroSort method, based on technology developed in livestock research in the 1980s. For a little over a $1000, you get a 60 to 65% chance of choosing your baby's gender.

To get to the 99%-plus chance of success, you have to turn to in-vitro fertilization. Eggs are harvested from the mother and matched up with sorted sperm. The resulting embryos are screened to confirm gender before one is re-implanted. Successful, yes, but you have to be pretty determined about gender selection to spend the approximately $20,000 and undergo an invasive procedure.

All in the timing?

No wonder, then the enduring popularity of the Shettles method. Dr. Shettles argues, in his book How to Choose the Sex of Your Baby, that male sperm are smaller, weaker and faster than the female sperm, which are bigger, stronger and slower. Many recommendations follow from this observation, but the most important involves timing of conception: the closer to ovulation you have intercourse, the higher the likelihood that you will have a boy, since male sperm are faster and therefore likely to reach the egg first.

Shettles claims his method has a success rate of 80-85% for boys and 75-80% for girls. The scientific evidence is mixed, but does seem to indicate some relationship between time of conception and sex of the offspring.

For timing conception, you again have an array of strategies, the most reliable and convenient of which is a simple fertility monitor. The most accurate fertility monitors practical for home use measure electrolytes in saliva. They retail for less than $300 and allow a woman to easily pinpoint her time of conception days in advance.