Can Supplements Actually Improve Your Sperm's Forward Movement? Here's What the Research Shows

Part 1 of the SwimScore Fertility Series: Progressive Motility

Search "male fertility supplements" and you'll find two camps. Brands citing every study that supports their product. Contrarian headlines declaring supplements are useless. Neither is particularly helpful if you're trying to understand what's actually going on with your fertility and what, if anything, is worth doing about it.

We started SwimScore because we think men deserve better than that. We use CLIA-certified labs, the same federal standard required of the labs your doctor uses, and we measure against WHO 6th Edition clinical thresholds. When we write about what might move your numbers, we follow the science honestly. That means sharing what the research supports, what it doesn't, and where we land practically.

What Progressive Motility Is and Why It Matters

When you get a semen analysis, you'll see a few different motility numbers. Total motility counts every sperm that's moving, including ones spinning in circles or drifting sideways. Progressive motility is more specific. It measures the percentage of sperm swimming forward, either in a straight line or in large purposeful arcs. The WHO 6th Edition sets the clinical reference threshold at 32%.

Research consistently identifies progressive motility as one of the strongest predictors of natural conception. A large population study found that men with progressive motility above 32% were significantly more likely to achieve pregnancy within 12 months of trying than men below that threshold. (Larsen et al., Human Reproduction, 2000) A separate analysis found that progressive motility was a better predictor of natural pregnancy than total sperm count in couples not using assisted reproduction. (Slama et al., American Journal of Epidemiology, 2002) Among all standard semen parameters, progressive motility consistently shows the strongest independent association with time to pregnancy in naturally conceiving couples.

The reason is anatomical. To reach and fertilize an egg, sperm must travel from the cervix, through the uterus, and into the fallopian tube. Sperm that are moving but not going forward get filtered out almost immediately in the cervix. Only sperm with purposeful forward momentum make it through. This is why progressive motility is the number fertility specialists pay closest attention to, and why it's the first metric in our series.

What Drives Progressive Motility

The energy for forward movement comes from the mitochondria packed into the midpiece of the sperm, the section between the head and the tail. When the midpiece is working properly, the tail generates the coordinated, powerful strokes needed to propel the sperm forward. When it isn't, sperm may still move but they don't go anywhere useful.

The primary reason that engine fails is oxidative stress, the buildup of reactive oxygen species, unstable molecules generated by inflammation, environmental toxins, heat, and poor diet that accumulate in semen and damage sperm cells. Sperm are particularly vulnerable because they carry almost no protective cytoplasm. The damage shows up directly in progressive motility: lower energy output, weaker strokes, less forward direction.

This is the biological foundation for why antioxidant supplementation is the main research focus for progressive motility. Reduce oxidative damage, restore mitochondrial function, improve forward movement. The question is which supplements actually deliver on that.

What the Research Shows

The supplement literature in male fertility is genuinely mixed, and we think it's worth being upfront about that rather than pretending it's cleaner than it is. Different studies reach different conclusions depending on their methodology, the populations they studied, and what outcomes they measured. Our job is to read across all of it and tell you what we actually think.

Here is where we land.

L-carnitine has the most specific and consistent evidence for progressive motility. Carnitine is produced naturally in the epididymis, the structure where sperm mature, and its primary role is shuttling fuel into the mitochondria that power the sperm tail. When carnitine levels are low, sperm have the physical structure to swim but not enough energy to do it properly.

What makes carnitine particularly compelling in the research is that it improves progressive motility specifically, not just general movement. The Salas-Huetos 2018 meta-analysis of randomized clinical trials found that carnitines were the only supplement to significantly improve progressive motility, with a mean improvement of 7.45%. (Salas-Huetos et al., Advances in Nutrition, 2018) A 2022 network meta-analysis of 23 randomized controlled trials involving 1,917 patients ranked L-carnitine first for motility improvement across all antioxidants tested, with a mean difference of 6.52%. (Li et al., Frontiers in Endocrinology, 2022) The mechanism and the clinical data point in the same direction consistently. That doesn't happen often enough in this field to ignore when it does.

CoQ10 is the other supplement we have meaningful confidence in. It operates inside the mitochondrial membrane, generating the energy that powers the sperm tail while simultaneously protecting it from oxidative damage. A 2025 meta-analysis of nine randomized controlled trials in 781 men found CoQ10 significantly improved total motility. (World Journal of Men's Health, 2025) The earliest well-designed study in this area found that six months of CoQ10 supplementation in men with low progressive motility improved forward motility from 9.13% to 16.34%. (Balercia et al., as cited in Salvio et al., Antioxidants, 2021) CoQ10 also consistently reduces sperm DNA fragmentation, which frequently co-occurs with low progressive motility and compounds fertility challenges further.

What We Are More Skeptical About

Omega-3 fatty acids are frequently recommended for motility. We are not convinced for progressive motility specifically. The concentration data is more credible, as omega-3s are incorporated into sperm cell membranes and there is a plausible structural mechanism. But when the Henriksen 2025 meta-analysis restricted its analysis to placebo-controlled trials of 12 weeks or more, omega-3s showed no significant motility improvement. If sperm concentration is also a concern, they are worth considering. For progressive motility as the primary target, we would focus elsewhere first.

Selenium has a real mechanism. It protects sperm from hydrogen peroxide, one of the more damaging oxidative molecules in semen, and the evidence shows it improves total motility. But the progressive motility evidence specifically is thin, and the effect sizes are smaller than for carnitine and CoQ10. It makes sense as part of a broader stack but not as a lead intervention for PR.

Vitamin D, vitamin E, and zinc and folate combinations showed no significant motility improvement in the Henriksen 2025 analysis. There are other reasons to understand your vitamin D and zinc levels, as both have hormonal implications worth knowing about, but for improving progressive motility directly the evidence is not there.

The Pregnancy Question

We know the following:

• Progressive Motility is an important metric in conception
• Certain supplements have been proven to improve Progressive Motility

The logical question that researchers wanted to test was whether they can prove this also leads to improved pregnancy rates. Interestingly, the results are mixed. 

The most comprehensive recent study in this space, Henriksen et al. 2025, covered 50 randomized controlled trials and over 4,800 participants and found that while carnitine and CoQ10 did improve motility, they did not find a significant statistical effect of any supplement on pregnancy or live birth rates. 

Many factors may go into this. Progressive motility is only one input into a process that also depends on the female partner's age and ovarian reserve, timing, embryo quality, implantation, sperm DNA fragmentation, morphology, and count. No single parameter determines whether a couple conceives in any given cycle.

Progressive motility matters for natural conception. That is well established in the research. Certain supplements improve it. That is also well established. Whether improving it directly improves pregnancy odds is not proven yet.

What we do know is that sperm quality is one of the few inputs in this process that men can actually do something about. Progressive motility is measurable, it responds to intervention, and improving it puts better biology into every cycle.

How to Think About This Practically

How to Think About This Practically

Progressive motility is one of the most important fertility metrics. Certain supplements demonstrably improve it. The logical conclusion - that improving it improves your odds of conception is biologically sound, and many researchers believe it to be true. It just hasn't been proven with statistical certainty yet, likely because pregnancy involves so many variables beyond any single sperm parameter.

If you want to act on the evidence that exists, here is how we would approach it.

Start with L-carnitine and CoQ10. These are the two supplements with the most consistent motility evidence, the clearest mechanisms, and the most direct relevance to progressive motility specifically. Everything else is secondary.

Run it for at least 12 weeks. Spermatogenesis takes approximately 72 days. Any intervention assessed before that window closes isn't measuring a full cycle of effect, which is why many negative supplement studies are difficult to interpret. Duration matters more than most people realize.

Check the full picture alongside your sperm parameters. Low PR with abnormal testosterone or FSH points to a different underlying issue than low PR with normal hormones. Supplements address oxidative stress at the sperm level. They don't resolve hormonal disruption upstream. This is why we run a hormone panel alongside every semen analysis — knowing which situation you're in determines what makes sense to do next.

Measure before. Measure after. This is the step most people skip. Without a baseline you can't know if anything changed, and without a follow-up analysis after 12 weeks or more you're guessing. The goal is to know.

Our Take

Progressive motility is one of the most important and most improvable parameters in male fertility. The research consistently identifies it as a meaningful predictor of natural conception. The evidence that carnitine and CoQ10 improve it is consistent and credible. Whether that improvement translates directly to better pregnancy odds isn't fully established yet. 

What we believe is straightforward. Improving the inputs you can control is rational. Progressive motility is measurable, it responds to targeted intervention, and it is one of the few fertility levers genuinely within your reach. Your results are the starting point. Everything else follows from knowing your numbers.