First, let’s run through the two-minute junior high school biology class:
A baby’s gender is established when it receives the two sex chromosomes from its parents. Its mother has two x chromosomes (from which the egg already has one) and the father has an x and a y chromosome (so they can receive either one). Just like its parents, if the combination is xx, the baby is a girl; if it is xy, the baby is a boy. Studies state that men’s sperm are divided 50/50 between the x carriers and y carriers, although in some rare cases, the ratio is skewed.
So we come to the question: how can you affect which sperm will fertilize the egg? Listed below are a number of at-home techniques, followed by medical procedures, that all claim to have an impact on your resulting bundle of joy.
At Home – Non-Invasive Techniques
This decades-old method is the most popular of at-home techniques since it is based on the scientific premise that sperm carrying the male y chromosome and sperm carrying the female x chromosome have different properties. The theory behind the method is that couples can take advantage of these differences and influence which sperm will make it to the lucky egg.
Further, the late Dr. Landrum Shettles claimed “authoritative scientific studies” and “compelling anecdotal evidence” that endorse the method’s success.
Here’s the gist of the method: The “male” sperm are apparently faster and smaller, but they die more quickly than their counterparts. The “female” sperm are slower but stronger, with the ability to endure the acidic cervical environment before fertile cervical fluid is produced.
Based on these traits, it is recommended that couples who are hoping for a girl have intercourse two to three days prior to anticipated ovulation and not have intercourse again until two days after ovulation. The presumption is that the x-carrying sperm might be slower than their counterparts, but they will still be around when the egg makes its appearance. By that time, the y-carrying sperm will have died.
In hopes of a boy, the recommendation is to schedule intercourse right around ovulation. That way, those fast x-carrying sperm will beat out their female counterparts and speed their way to the awaiting egg.
There are other recommendations for the Shettles Method as well:
Position: Deeper penetration for a boy (to deposit those quick sperm closer to their goal); more shallow for a girl (so the strong female-laden sperm will outlive the male swimmers on their longer journey to the egg).
Female Orgasm: Go for it if you’re hoping for a boy (since the alkaline secretions increased by a female orgasm create a more favorable environment for those princes-to-be); hold off for a girl (since these sperm prefer the acidic setting).
Unfortunately, if you’ve been having trouble conceiving, you may find that trying to time your conception may only extend your fertility efforts.
The following methods are based less on scientific merit and more on folklore and cultural practices:
You may have heard that if you want a girl, you should stick with sweets and calcium-rich foods, and if you’re hoping for a boy, you should consume salty foods and red meat. Aside from studies that show that diet has no relationship to the potential gender of your baby, severely limiting your diet (or overindulging in salt if you’re on a salt-restricted diet) could have adverse effects on someone who should be in optimal health to conceive a child. Verdict: Not worth the trouble.
Another belief is based on the Chinese calendar. There is a predetermined chart, with ages running across one axis, and the months of the year on another. The chart is then filled with female/male squares, and matching up your age at conception with the month of conception will apparently tell you the gender of your child. (For example, a thirty-year-old conceiving in March will deliver a girl.) Unfortunately, two different sites showed two different results for a thirty-year-old conceiving in February, so even if the theory has any merit, the chart you are referring to might be inaccurate. Verdict: Try for fun, not for results.
Phases of the Moon
Following the presumption that alkalinity or acidity around the egg can affect which sperm will be successful, there is the theory that the movement of the moon can affect these changes in a woman’s womb. The theory: A full moon will aid you in your quest for a baby girl; a quarter moon will bring you a son. Verdict: A tough one if it’s cloudy in your area.
Mother’s Age at Conception
This ancient Mayan belief has to do with the mother’s age at conception and the year of conception. If both are even or both are odd, the baby will be a girl. However, if one is even and the other odd (or vice versa), the baby will be a boy. Verdict: Difficult to prove as anything but coincidence.
Conception and Aggression
In this old wives’ tale, if the mother-to-be was the aggressor during conception, she would welcome a baby boy, whereas a girl would result from the father-to-be acting as aggressor. Verdict: We thought this was called role play.
If those “male” sperm are fast but fragile, the speculation here is that heat will kill these delicate swimmers. Therefore, if you are hoping for a boy, have your partner avoid hot tubs, tight clothes, laptops and anything else that could raise his internal temperature. Verdict: Men should avoid overheating the genital area regardless of what gender they desire.
An ancient practice of Greek philosophers (and carried out by some 18th-century French men) was the tying of string around the left testicle in hopes of a boy. This technique was based on the belief that male and female sperm lived separately in each testicle: the y chromosome sperm in the right and the x chromosome sperm in the left. Aristotle apparently advised that a son would be produced if conception occurred in the north wind, a girl in the south wind. Verdict: If you need a verdict on this one, we have a bridge …
In Doctor’s Office – Medical Intervention
Despite the ethical dilemma that has saddled the topic of gender selection, there is a strong interest in today’s available procedures. Some couples are looking to avoid a genetic disease that is more common in one gender than the other. Other couples are hoping for a boy after having three girls or a girl after generations of sons.
If you do opt for medical intervention in your quest for a girl or boy, you are looking at procedures that involve assisted reproductive technology (ART) either in the form of intrauterine insemination (IUI) or in-vitro fertilization (IVF). Those are a lot of abbreviations!
The following are listed from least to most invasive, and their success rates follow accordingly, from less effective to nearly 100 percent effective.
The underlying theory behind this technique is sperm carrying an x chromosome are heavier than their y chromosome-carrying counterparts. Therefore, if the sperm could be separated based on their density, the desired sperm could then be implanted. The “spinning” part comes into play because the separation takes place while the semen is spun. Often, sperm is separated from semen as a preparation process for insemination or IVF since these procedures can remove the weaker or slower sperm and/or any damaged material. In these cases, gender selection is a secondary (and usually optional) result of these treatments.
Different variations of this method include:
- Ericsson Albumin method
- Percoll density gradient centrifugation
- Standard and modified “swim up” technique
Success Rates: Reports vary, with many countering that these methods do not greatly alter the 50/50 chance you would have without the treatment.
You Should Know: These procedures are usually followed up with fertilization by insemination, not IVF.
The most successful version of this technique is called flow cytometry and has been largely conducted by the Genetics & IVF Institute under their “MicroSort” program.
The MicroSort procedure involves staining the sperm with a fluorescent dye, identifying them under an ultraviolet light, and then sorting them based on their differences.
The theory is that the x-chromosome is larger than the y chromosome, so the sperm carrying an x chromosome will absorb more dye than those carrying a y chromosome. When they are run through the ultraviolet light, the x chromosome sperm (with more dye) glows brighter than the y chromosome sperm. These “x” sperms are then given a positive charge (making them glow red), and the “y” sperm receive a negative charge (making them glow green). The red and green sperm are then separated and the couple can choose to implant the gender of their choice.
Success Rates: Reported at approximately 85 to 90 percent for girls and 60 to 75 percent for boys.
You Should Know: While years of animal testing have failed to show any negative effects to the fluorescent dye or exposure to ultraviolet lasers, studies have not yet been conducted on long-term consequences to human cells.
Additionally, the procedure is still considered to be under clinical trial, so you must meet enrollment qualifications in order to qualify. The expectant parents need to be married and test negative for HIV and Hepatitis B and C, in addition to other criteria.
PGD: Pre-Implantation Genetic Diagnosis
While PGD’s primary objective has been to screen embryos for gender-related diseases, the procedure is also widely used for gender selection.
The technique adds a step to the in-vitro fertilization (IVF) process. After the harvested eggs have been fertilized, the eggs develop for three days and are then screened for gender (as well as multiple genetic diseases). The desired gender embryo(s) is then implanted in the woman’s uterus.
Success Rate: Nearly 100 percent.
You Should Know: You cannot use this method if you are planning on conceiving via insemination. All procedures must be done via in-vitro fertilization, which means that the expectant mother needs to do all of the hormonal preparation involved with such a procedure.