Popularized for decades, the Shettles method promises to increase the chances of having a boy or a girl by adjusting the timing of sexual intercourse. An attractive theory, but one that scientific research struggles to confirm.
An ancient promise, between beliefs and desire for mastery
Choosing the sex of your child is not a new idea. Long before the progress of modern medicine, traditions, calendars and sometimes improbable recipes were already circulating from generation to generation.
In the 1960s, a more “scientific” approach emerged with the Shettles method. Its principle is based on a supposed distinction between sperm carrying the X chromosome (female) and those carrying the Y chromosome (male). The latter would be faster but more fragile; the first, more resistant but slower.
From this hypothesis comes a strategy: having sexual intercourse on the day of ovulation would promote the birth of a boy; a few days before, that of a girl.
The idea appeals because it gives an impression of control in a process often experienced as uncertain. It also reassures by offering an active role to future parents. But behind this apparent biological logic, the scientific reality is much more nuanced.
What the studies really say: a weakened hypothesis
Over the years, the scientific community has looked into this theory. And the results are far from validating the initial promises.
As Léa Pateras-Pescara points out in a video published on April 8, 2026:
“In the laboratories, we have no profound… significant differences between the longevity and the speed of girl spermatozoa or boy spermatozoa”.
In other words, the very foundations of the Shettles method – the difference in behavior between sperm X and Y – are not firmly established.
However, research shows an essential point: synchronizing intercourse with ovulation increases the chances of conceiving… but without influencing the sex of the child.
This gap between belief and scientific reality can be destabilizing. Because it reminds us of a truth that is sometimes difficult to accept: despite medical advances, a part of human reproduction still escapes any control.
Should we therefore abandon all attempts? Léa Pateras-Pescara’s response is pragmatic:
“Is it worth a try if you enjoy it? Why not ? As long as we stay relaxed, because stress influences fertility much more than the X or Y chromosome.”.
An invitation to put things into perspective, without feeling guilty.
Getting to know your body: a much more essential issue
If science today does not allow you to choose the sex of your child in a natural way, it highlights another lever, often underestimated: knowledge of your own body.
Track your menstrual cycle, understand the signs of ovulation, identify your fertile periods… These elements do not guarantee a boy or a girl, but they play a key role in the chances of conception.
And above all, they participate in a form of reappropriation of the body, often valuable in the sometimes trying journey towards parenthood.
Because behind the techniques and theories, there are women, couples, expectations, sometimes disappointments. Stress, obsession with results, pressure – social or personal – can become much more concrete obstacles than genetics themselves.
In this context, the issue is no longer about “choosing”, but about understanding, supporting, and preserving an emotional balance.
A science in motion, between limits and hope
Today, the data is clear: apart from highly regulated medical techniques (such as preimplantation diagnosis for specific indications), there is no reliable method for choosing the sex of your child.
But this conclusion should not be experienced as an end. On the contrary, it opens up a broader reflection on our relationship to science, control, and uncertainty.
Accepting that not everything is controllable also means giving back room for the unpredictable, for the unique story of each birth.
And remember that, behind the question of sex, there is above all a desire for a child — in all its complexity, its fragility, and its beauty.