Does testosterone therapy affect baby gender? We checked

What did @daviddemesquita actually say?

The claim is that SHBG levels determine the odds of conceiving a boy or a girl. Specifically: elevated SHBG raises your chances of a boy, low SHBG raises your chances of a girl. He then walks through dietary and hormonal levers, saying "low carb diets are known to actually increase SHBG levels" and that "male testosterone will drastically reduce down SHBG levels," which he frames as increasing girl odds. He also brings in HCG as a testosterone and estrogen modifier. The caption adds a definition of SHBG as "red blood cells that help carry hormones," which is wrong on its face before we even get to the sex-selection claims.

Worth noting his stated credentials are working in "the medical and functional community" and with professional athletes. That doesn't make him a reproductive endocrinologist, and this topic requires that kind of precision.

Does the science back this up?

Loosely, partially, and with enormous caveats. There is a real body of research linking maternal glucose and metabolic status to offspring sex ratios at the population level. The SHBG-sex-selection link in men specifically is far thinner. The most cited work here is Mathews et al. (2008, Proceedings of the Royal Society B), which looked at maternal breakfast consumption and glucose, not paternal SHBG. Applying that logic to male SHBG as a causal dial for sex selection is a significant inferential leap.

On SHBG biology, he's directionally correct that low carbohydrate intake tends to raise SHBG and high carbohydrate intake tends to lower it, supported by Holt et al. (2000, American Journal of Clinical Nutrition). Exogenous testosterone suppressing SHBG is well established. But "suppressing SHBG therefore changes your baby's sex" is not a proven clinical conclusion. Population-level associations are not individual-level guarantees.

What did they get wrong (or right)?

The caption definition is flatly wrong. SHBG is sex hormone-binding globulin, a glycoprotein produced by the liver. It is not a red blood cell, and calling it one isn't a simplification, it's a different thing entirely. That kind of error undermines credibility on the more nuanced claims.

The testosterone claim deserves scrutiny too. He says exogenous testosterone reduces SHBG and increases girl odds. Men on TRT typically have fertility issues to begin with because exogenous testosterone suppresses LH and FSH, reducing sperm production. Recommending testosterone as a preconception strategy to skew sex ratio is not just unsupported, it's likely counterproductive. You can't select a sex with sperm you're not producing.

He does get the SHBG-diet direction right. The claim that elevated estrogen raises SHBG is also pharmacologically accurate. And flagging HCG's dual effect on testosterone and estrogen shows some functional literacy, even if the "net equivalent" conclusion is vague and unsupported by specific data.

What should you actually know?

The honest answer is that no dietary or hormonal intervention has been proven in controlled human trials to reliably shift the male-to-female birth ratio at the individual level. The Shettles method, pH-based timing, and various dietary protocols have decades of popular traction and weak clinical evidence. A Cochrane review found no reliable evidence that any preconception sex-selection method short of preimplantation genetic testing actually works.

If you're on TRT and trying to conceive, the conversation you need to have is with a reproductive urologist, not a TikTok video. Exogenous testosterone almost universally suppresses spermatogenesis. HCG is sometimes used to preserve or restore sperm production during TRT, but dosing and monitoring require clinical oversight. The sex of your future child is not a variable you can reliably adjust with a low-carb diet.

• SHBG is a liver-produced glycoprotein, not a red blood cell or related to red blood cells in any way.
• Diet does influence SHBG levels, but influencing SHBG does not equal controlling offspring sex.
• Men on exogenous testosterone face significantly reduced fertility, which is a bigger problem than sex ratio optimization.
• Preimplantation genetic testing during IVF remains the only clinically validated method for sex selection.

Bottom line

This video mixes real endocrinology vocabulary with reproductive biology claims that the evidence does not support at an individual level. The direction on some SHBG associations is roughly right. The conclusion that you can meaningfully steer your baby's sex through SHBG manipulation is not proven. And the caption's definition of SHBG is simply incorrect. Engaging with this content as a how-to guide for sex selection would be a mistake.