"All I want is a healthy baby."

Although this wish tops every pregnant woman's list, many moms-to-be harbor a secret, or not so secret, desire for a boy or a girl.

At some fertility clinics, high-tech sperm-spinning can yield the preferred gender up to 90 percent of the time. But for couples who can't afford this pricey procedure, or who shudder at the idea of "playing God," employing one of the more natural sex selection methods may help them get the baby they want inexpensively, without stepping on Mother Nature's toes.

Old Wives' Tales
Folklore is full of creative, often wacky, suggestions for choosing a baby's sex. According to the Old Wives, women should eat meat and salty food to get a boy, or splurge on desserts to get a girl. Couples supposedly are more likely to conceive sons if they make love standing up or when there's a quarter moon. Conversely, daughters are in the picture if partners use the missionary position or have sex during a full moon.

The Chinese conception chart, which has been around for some 700 years, tells women what dates will result in boy or girl conceptions based on the mother's age and the month of conception.

These methods are entertaining to read about, and in some cases to practice, but none has any legitimate scientific merit. For example, going by the Chinese conception chart, this writer's son should have been a daughter.

The Shettles Method
In the early 1960s, Dr. Landrum B. Shettles published a groundbreaking report on the distinctive characteristics of Y-bearing (boy-producing) and X-bearing (girl-producing) sperm. He asserted that the Y sperm are lighter in weight, swim faster, but die sooner; the X sperm are heavier, swim slower, but live longer. Shettles expanded this central thesis into a low-tech method of gender selection. His resulting book, How to Choose the Sex of Your Baby, co-written by David M. Rorvik, was first published in 1970 and since has become the sex-selection bible for couples interested in non-invasive, low-tech family planning techniques. In the 1997 edition, Shettles claims a conservative 75 percent success rate for partners who employ his method scrupulously.

To take advantage of sperm speed and staying power, the timing of intercourse plays a critical role in achieving the desired gender. To get a boy, Shettles advises couples to have sex as close to ovulation as possible. During ovulation a woman's vaginal and cervical fluids become alkaline, a condition that makes conception more favorable for either sperm, but especially for the less hearty Y sperm. And because the Y sperm move quicker than the female-producing sperm, they are more likely to win the race to the egg. Prior to and following ovulation, vaginal and cervical secretions are acidic. If intercourse occurs under these conditions, the heartier X sperm are more apt to survive in the reproductive tract for a couple of days until the egg arrives.

Because many women don't know when they're ovulating, Shettles suggests they track several cycles to observe their body's signals before attempting conception. By checking the condition of her cervical mucus (CM), also known as cervical fluid (CF), and tracking her basal body temperature (BBT) for a few months, a woman should be able to pinpoint the day of ovulation and the fertile days leading up to it.

Ovulation kits available in pharmacies also can determine when a woman is ovulating, but these kits are expensive and may not be accurate for women with irregular cycles.

How to Get a "Shettles Girl"
According to Shettles, girls are harder to come by than boys. Couples need to be patient; conceiving a girl may take several months. The reason for this is that partners trying for a daughter need to stop having sex at least 2 days before ovulation, so more X sperm than Y sperm will be around to meet the egg. Even though the Xs have better staying power, it's tougher (but not impossible) for either sperm to last more than a few days. That said, the basic method to conceive a girl is this:

Immediately after a woman's menstrual period ends, she and her partner should have intercourse frequently (at least every other day) until 48 hours before ovulation. Shettles stresses that continuing to have sex beyond this point diminishes the chances of getting a girl.

How to Get a "Shettles Boy"
In a nutshell, couples hoping for a boy should do the following:

Either abstain from sex or use condoms until 4 days before ovulation. After this point, abstain entirely until 12 hours prior to ovulation; this sexual respite acts to boost a man's sperm count, a condition that Shettles maintains favors male sperm. During the 12-hour ovulatory window, a couple should have sex, preferably just once. After this, partners must use condoms if they have intercourse again in the next several days.