The Shettles Method for Gender Prediction

The Shettles Method is one of the most widely discussed natural gender selection theories. Developed by Dr Landrum Shettles in the 1960s, it suggests that the timing of intercourse relative to ovulation can influence whether you conceive a boy or a girl. While popular with hopeful parents, its scientific backing remains limited.

Table of Contents

1. What Is the Shettles Method
2. How It Supposedly Works
3. What Does the Evidence Say
4. How It Compares to Other Gender Prediction Approaches
5. Frequently Asked Questions

What Is the Shettles Method

The theory follows from this: if you could time intercourse so that one type of sperm has a survival advantage by the time the egg is released, you could theoretically tilt the odds in favour of a boy or a girl. Shettles published this idea in a popular book in the 1960s and it became widely known among couples hoping to influence the sex of their child.

It is important to understand from the outset that this is not a medically endorsed method, and the evidence behind it is not strong. No NHS body recommends it for gender selection.

How It Supposedly Works

For a boy: Shettles recommended having intercourse on the day of ovulation or the day after. The theory is that the faster Y-bearing sperm will reach the egg first, before the X-bearing sperm catch up.

For a girl: Shettles suggested having intercourse two to four days before ovulation, then abstaining until after ovulation has passed. The theory is that by the time the egg is released, the shorter-lived Y-bearing sperm will have died off, leaving the more resilient X-bearing sperm to fertilise the egg.

Beyond timing, Shettles also claimed that factors such as sexual position, the woman's orgasm, and vaginal pH could influence which sperm reached the egg first. These additional claims are even less supported by evidence.

To apply the timing element, you need to know when you are ovulating. This is typically done using ovulation predictor kits (OPKs), which detect the luteinising hormone (LH) surge that occurs 24 to 36 hours before ovulation. Basal body temperature (BBT) tracking can also help, though it usually only confirms ovulation after it has already happened rather than predicting it in advance.

What Does the Evidence Say

One issue is that the original claims about X and Y sperm characteristics have not held up under modern scrutiny. Research using advanced sperm analysis has not found the speed and survival differences that the Shettles theory relies on. At the same time, a baby's sex is determined entirely by which sperm fertilises the egg — a process that involves far more biological variables than simple timing.

This does not mean trying the method is harmful. Timing intercourse around ovulation is something many couples do anyway when trying to conceive, and if you happen to prefer one approach to timing, there is no medical downside to following it. Just understand that any outcome is likely to reflect the natural approximately 50/50 odds rather than a genuine effect of the method.

How It Compares to Other Gender Prediction Approaches

• Nub theory — reads the angle of the genital tubercle on an 11 to 14 week ultrasound scan; it predicts after conception, not before
• Ramzi theory — based on the position of the placenta at an early scan; again, used during pregnancy
• NIPT blood test — a highly accurate clinical blood test taken from around nine weeks of pregnancy; this is the most reliable early method for determining sex
• 20-week anatomy scan — the sonographer may be able to tell you the sex from the detailed scan, though this is not guaranteed and depends on the baby's position

None of these overlap with the Shettles Method. If you are already pregnant, the Shettles Method is not relevant to you — you are looking for prediction methods, not selection methods.

Frequently Asked Questions

Independent studies have not consistently shown that it works better than chance. Most researchers who have looked at this area conclude that the sex of a baby is not reliably influenced by the timing of intercourse relative to ovulation in the way Shettles described. Many couples try it anyway as a harmless, low-cost approach, but should do so with realistic expectations.

Is it safe to try the Shettles Method?

Timing intercourse is entirely safe. There is no medical risk to following the Shettles approach, though there is one practical consideration: if you are trying to conceive a girl and you abstain around ovulation as the method suggests, you may reduce your chances of conceiving in that cycle. Fertility specialists generally advise having intercourse regularly throughout the fertile window to maximise conception chances overall.

Can the Shettles Method replace nub theory?

No — they serve completely different purposes. The Shettles Method is used before conception in an attempt to influence which sex is conceived. Nub theory is applied to an ultrasound image after conception to predict the sex of an already-developing baby. If you are already pregnant, the Shettles Method has no relevance; what you want is a prediction method such as nub theory, Ramzi theory, or a NIPT blood test.

Always speak to your midwife or GP for advice tailored to your personal circumstances.

Related articles:

• Nub Theory Explained
• Ramzi Theory
• Gender Blood Test at 9 Weeks