The Shettles Method based on the premise that sperm carrying the X and Y chromosomes have different characteristics and that under different circumstances either X- or Y-chromosome-carrying sperm will be more likely to fertilize the egg.
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According to Dr.Shettles you can influence the reproductive environment to favor one or the other. Here's how the theory goes:
It is the sperm that fertilizes the egg that will determine the sex of your baby. Sperm that carry the X-chromosome will make a girl and sperms that carry the Y-chromosome make a boy.
The Y-chromosome-carrying sperm (the ones making a boy) are said to:
- Be faster and smaller than the X-chromosome carrying sperm
- Die faster than the X-chromosome-carrying sperm
The X-chromosome-carrying sperm are said to:
- Be slower than the Y-chromosome carrying sperm
- Be better able to withstand the acidic vaginal environment before fertile cervical fluid is produced.
According to Shettles, you can time intercourse, choose a sexual position that favors conception of your preferred sex and influence the reproductive environment to increase the likelihood of conceiving your preferred sex.
The BabyMed Gender-Choosing Calendar helps you interactively plan for the right gender.
These are the suggestions from Dr. Shettles:
To Get A Boy
- Time intercourse as close to ovulation as possible: The idea is that since the Y-chromosome sperm are faster than the X-chromosome sperm, there will be more Y-chromosome sperm who reach the egg, making it more likely that a Y-chromosome carrying sperm will fertilize the egg.
- Abstain from intercourse for four to five days prior to ovulation. Have intercourse only just at the time of ovulation and just before.
- Have intercourse that allows for deep penetration. Shettles recommends rear-entry (aka, “doggy-style”). The idea is that the sperm will be deposited closer to the cervix where cervical fluid is most friendly to the Y-chromosome sperm and where the “boy sperm” are more likely to survive since there is less distance to travel.
- Men avoid tight clothes: heat kills off both types of sperm, but will kill off the less protected, smaller Y-chromosome sperm faster, according to Shettles.
- Women have an orgasm: According to Shettles, female orgasm increases the alkaline secretions in the vagina that are favorable to the Y-chromosome carrying sperm. Shettles recommends having an orgasm before or at the same time as the male partner.
To Get a Girl
- Have intercourse 2-3 days before ovulation and avoid intercourse just before ovulation until 2 days after ovulation and when you have peak cervical fluid: The idea is that when you have sex a few days before ovulation, only the X-chromosome “girl sperm” will be left in the female reproductive tract waiting to fertilize the egg when it is released.
- Have intercourse with shallow penetration: Shettles recommends “missionary position”or any position that will deposit the sperm slightly away from the cervix, giving advantage to the longer living, but slower X-chromosome-carrying sperm.
- Women avoid orgasm: Shettles suggests women avoid orgasm because it makes the vaginal environment more alkaline, and less acidic and is disadvantageous to the X-chromosome “girl sperm”.
- If you are taking longer than expected to conceive, it is generally not recommended to attempt any kind of sex selection as it can increase the time it takes to conceive.