When the sexual relationship is made naturally and spontaneously, the possibility of having a girl or a boy is approximately 50/50 (in some regions a little more women are born and a little more men are born).
However, due to cultural influences, personal preferences or for health reasons, some families seek natural or artificial methods that can divert this 50/50 ratio in order to increase the probability that the child is born of a certain sex.
The choice of the sex of the baby is a very controversial issue, either because many of the techniques lack scientific basis or because our society still presents niches with great sexist bias, giving greater value to male children.
Not always, however, preference for a particular sex comes with few noble reasons, such as the devaluation of women. A couple that already has a child of a certain sex has every right to wish that the next child is of the opposite sex. On the other hand, some genetic diseases are linked to the sex chromosomes, what the choice of sex of the baby is a way to prevent the genetic defect inherited by the son or daughter.
Fertilization techniques currently used in large reference centers present some problems that prevent their routine use in the general population. In addition to any ethical discussion, they are not 100% effective, are carried out through invasive procedures, are not exempt from side effects and still cost a few thousand dollars.
Therefore, some “home” or “natural” methods are still very popular, although it is not usually indicated by doctors specializing in fertility. Within these options, the most famous is the Shettles method.
What Is the Shettles Method
The Shettles method was created in 1960 by Dr. Landrum B. Shettles and popularized by the book “How to choose the sex of your baby,” published in 1971 by the same author.
Dr. Shettles says that through his method it is possible to increase the possibility that a baby is male or female from the choice of the day of the menstrual cycle in which sexual intercourse occurs and the position used for intercourse .
According to the Shettles method, the sperm that contains the Y chromosome (male chromosome) is smaller, faster and less resistant than the sperm that contains the X chromosome (female chromosome). Following this logic, if the relationship occurs on the day of ovulation, the sperm with the Y chromosome would have more chances of fertilizing the egg. On the other hand, if the relationship occurs a few days before ovulation, sperm that contain the X chromosome would be more likely due to its greater ability to survive longer in the female reproductive system.
According to the defenders of the Shettles method, the success rate of this technique is approximately 75%.
How the Shettles Method Is Done
To do the Shettles method you must first estimate the day of your ovulation. In the guide of How to Calculate the Fertile Period and the Day of Ovulation we review some ways to estimate your fertile period.
If you want to have a girl, the ideal is to have frequent sex until 2 to 4 days before the estimated day of ovulation. After this period, you should avoid having new relationships (if you have them, it must be with a condom). As intercourse is celebrated days before ovulation, the more resistant “female sperms” will be the majority at the moment the ovum is available to be fertilized.
To have a child, for your time, the ideal would be to have sex on the day when you expect ovulation. As the “male sperms” are faster, they would reach the ovule first.
According to Dr. Shettles, the position in which the sexual act takes place could also have influence. When copulation is performed with the couple facing each other, the penetration is deeper and the sperm are released closer to the entrance of the uterus, in a less acid region of the vaginal canal. This position supposedly favors the fragile “male sperm.”
On the other hand, if the woman is facing away from the man at the time of intercourse, the sperm will be thrown into the initial portion of the vaginal canal, acid region and further away from the entrance of the uterus, which supposedly promotes the survival of the female sperm.
What Scientific Studies Say
There are no clinical studies that corroborate the claims of the defenders of the Shettles method. Actually, what the studies show is exactly the opposite, that is, the method does not work.
The most well-known study on the subject was published in 1995 in the prestigious scientific journal The New England Journal of Medicine ( Timing of Sexual Intercourse in Relation to Ovulation – Effects on the Probability of Conception, Survival of the Pregnancy, and Sex of the Baby – Allen J. Wilcox, MD, Ph.D., Clarice R. Weinberg, Ph.D., and Donna D. Baird, Ph.D ).
In this study with 221 women who were trying to become pregnant it was not possible to identify any pattern that could be related to the day of the relationship with the sex of the baby.
In addition to clinical studies in humans, the most current studies on sperm also do not support the claim that those containing the male chromosome are morphologically different or can move faster. Apparently, there is little difference in performance between “male” and “female” sperm.
The Shettles method is not a reliable technique for choosing the sex of the baby. In addition to being based on false assumptions about the differences between sperm that carry the male and female chromosomes, it lacks scientific basis and has been refuted by several clinical studies, which have shown that the date of intercourse does not have any relationship with the sex of the baby.
There is currently no simple or home-made method to select the sex of the baby. All scientifically based techniques are complex, expensive, restricted to a few reference centers and subject to prior evaluation by an ethics committee.