Does Retatrutide Affect Male Fertility? What the Trials Measured
Compare two retatrutide trials with a semen-analysis trial of semaglutide. See the registered-outcome check and why sperm morphology differs from pregnancy rates.
FormBlends Editorial Research · Updated 2026-10-03
Retatrutide is investigational and is not FDA-approved. FDA states that it cannot be used in compounding under federal law. FormBlends does not prescribe, compound or sell retatrutide.
Retatrutide's effect on male fertility is not established by the selected obesity trials. They enrolled men, but their reported and registered efficacy outcomes concern weight and metabolic measures rather than semen quality or conception. A small semaglutide trial did measure sperm morphology; it studied a different drug and a specific population, so its result cannot be reassigned to retatrutide.
Which studies actually measured a reproductive endpoint?
| Study | Population and follow-up | What was measured | What it establishes for this question |
|---|---|---|---|
| Retatrutide phase 2 obesity trial, 2023 | 338 adults; 51.8% men; 48 weeks of treatment. | Primary weight change at 24 weeks; secondary weight outcomes at 48 weeks. | Includes men, but does not report a semen-quality or conception comparison. |
| Retatrutide TRIUMPH-2 phase 3, 2026 | 1,152 adults with obesity and type 2 diabetes, including 598 men; primary assessment at 80 weeks. | Body-weight change, with metabolic and other specified outcomes. | A larger and longer obesity study is not automatically a fertility study. |
| Semaglutide versus testosterone, 2025 | 25 men with obesity, type 2 diabetes and functional hypogonadism; open-label randomized comparison over 24 weeks. | Semen analysis and hormonal measures. | Relevant reproductive measurements, but a different intervention and selected patient group. |
Our check of the registered retatrutide outcomes
We reviewed the primary and secondary outcome-measure fields in NCT04881760 and NCT05929079 on October 3, 2026. The records contain 14 and 16 outcome entries, respectively. None names sperm concentration, morphology, motility, semen quality, testosterone, conception or live birth as its outcome measure.
This is a check of those two registered efficacy-outcome lists, not a claim about every retatrutide study or every safety event. Several entries repeat a measure at different time points. Thirty listed entries therefore does not mean thirty distinct reproductive tests, and male enrollment does not supply an unmeasured endpoint.
What the 25-man semaglutide trial found
The trial compared semaglutide with testosterone undecanoate in men who already had type 2 diabetes, obesity and functional hypogonadism. Median morphologically normal sperm in the semaglutide group changed from 2% to 4%; the reported within-group P value was .012. That is a 2 percentage-point change, or a doubling of the starting percentage, rather than a 2% relative improvement.
Both groups had increased total testosterone, while sperm concentration and total number decreased in the testosterone group. These endpoints illustrate why a higher testosterone result cannot, by itself, establish improved sperm production. The comparator, the 25-man sample and the open-label design remain part of the interpretation.
The study did not establish a retatrutide effect or a pregnancy or live-birth rate. Its semen result is useful context for a related drug, not proof that all GLP-1-based treatments have the same reproductive effect.
What would answer the retatrutide question directly?
A direct comparison would measure semen parameters before and after retatrutide, include an appropriate comparator and specify the participant population and follow-up. Hormonal change, sperm morphology, sperm count and conception are different outcomes. Weight reduction can motivate a research question without answering it.
Frequently asked questions
Does retatrutide cause male infertility?
The selected retatrutide publications and registered efficacy outcomes do not establish either that it causes male infertility or that it improves fertility. Not measuring an outcome is different from measuring no effect.
Did the phase 3 study include men?
Yes. TRIUMPH-2 enrolled 598 men within its 1,152-person obesity and type 2 diabetes study. Inclusion does not turn its weight endpoint into a semen analysis.
Can the semaglutide result be used as a retatrutide result?
No. The drug, receptor activity, study population and comparison differ. The 25-man study measures a related question and cannot establish retatrutide's reproductive effect.
Does improved sperm morphology prove a higher pregnancy rate?
No. The percentage of morphologically normal sperm and a conception or live-birth rate are different measurements. The selected semaglutide report does not provide that clinical outcome.
The sources here do not establish retatrutide as an approved treatment for this population or condition. Eligibility for research is determined by the individual protocol, not by a website BMI calculator or a telehealth assessment. No personalized suitability or adjustment of other treatment can be inferred from this article.