In the quest for high-quality embryos and viable pregnancies, sperm is critical, says Toronto-based reproductive endocrinologist Dan Nayot, who is chief medical advisor for fertility supplement company Bird&Be. And good sperm is about both quality and quantity. In a routine semen analysis, Nayot generally looks at the volume of semen (a combination of seminal fluid and sperm); sperm concentration (how many millions of sperm per millimeter); sperm motility (how many are actually moving, which is key); and sperm morphology (how many of the sperm look “normal”). “What’s really important for men is that you actually can’t tell if you have high quality sperm or even no sperm. You can’t tell by your anatomy, you can’t tell by your sexual performance, you can’t tell…visually by your semen,” says Nayot. “Until you assess it, you just don’t know.”

There is mounting evidence that sperm quality has been on the decline for decades. According to a 2017 study published in Human Reproduction Update, sperm counts in Western men dropped significantly between 1973 and 2011. (Among the study’s authors was reproductive epidemiologist Shanna H. Swan, who wrote the 2021 book Count Down, about how modern lifestyles have created a fertility crisis.) “A man today has half the number of sperm that his grandfather had,” says Menashe. A 2012 study on Danish men found that only one in four had optimal semen quality. “Poor sperm health is associated with increased time to pregnancy, increased risk of infertility and miscarriage, and higher chances that you’ll have to use advanced reproductive technology such as IVF,” says Joni Hanson Davis, founder of Beli, a prenatal vitamin brand. “Quality issues such as sperm DNA fragmentation can also put your baby at greater risk of birth defects and developmental disorders.” 

There are many causes of the downward slide in sperm quality, says Nayot. Part of it is diet, part of it is lifestyle (increased stress, smoking and cannabis use, plus being more sedentary) and part is environmental. “A lot of the estimates have to do with environmental toxins (BPAs, plastics, phthalates), then it’s the stress, the cellphone in the pocket, the laptop on the lap,” says Menashe. 

But Peter Schlegel, a urologist at New York’s Weill Cornell Medicine, says that while there’s a progressive decline in sperm quality with age, fertility potential is relatively well-maintained. The increase is in the chance that their offspring will have conditions like autism and schizophrenia. “We used to think that increase in birth defects didn’t occur until men were 50 or 60, but now it’s clear that it starts at 40, and subtle changes even start as early as 25,” says Schlegel.

Sperm are abundant, fragile and sensitive. “They’re sensitive to bad stuff, like heat and obesity and oxidative stress,” says Nayot, “but the reverse is that they also respond to the good stuff.” Steps for improving overall health, such as cutting back on drinking, exercising, mitigating stress and eating a nutrient-dense diet, will have a positive impact on sperm—and, some experts say, so can prenatal supplements. “Evidence shows that the most common cause of sperm deficiencies are nutrient shortages,” says Hanson Davis. It’s something that her brand, Beli, has tapped into, along with WeNatal, Needed and Bird&Be. All are creating products designed to include men in the preconception process in a new way. 

When it comes to men’s prenatal supplements, helping protect sperm DNA against oxidative damage and supporting their cellular health is key. “Oxidative damage in sperm is thought to contribute to upwards of 80 percent of male infertility,” says pediatric neurologist Sarah Rahal, the founder of Armra, a supplement brand made with bovine colostrum, which can help increase cell longevity. “It has been shown that infertile men with high levels of these free radicals in their semen have greater DNA fragmentation in their sperm and less normal sperm available,” says Rahal. 

Ryan Woodbury, co-founder of Needed, says antioxidants like vitamin C and CoQ10 are critical for shielding against oxidation; zinc, selenium, folate and omega-3 fatty acids all support sperm quality and structure; and folate and B12 are important for DNA synthesis. Nayot adds that the greatest amount of recent research has been around mitochondrial supplements like CoQ10. “Mitochondria is like the batteries in the cell, and the idea with the supplements is you maximize the energy, the efficiency of the mitochondria to help the sperm motility and concentration,” he says. 

But both Schlegel and Bobby Najari, a urologist at NYU Langone Health, are skeptical, saying that the research around the use of supplements isn’t substantive. “Theoretically antioxidants should be fabulous to help protect sperm. Unfortunately almost every study that we’ve done to demonstrate whether they actually increase fertility potential has been negative,” says Schlegel, noting that the idea that supplements are protecting sperm from damage is often enough of an incentive for men. “It’s reasonable to take them,” Schlegel says, “we just don’t have proof that it helps.” The group that these supplements may be most helpful for, says Najari, are men who aren’t getting the nutrients they need from their diets. “But what I often see is the very health-conscious man is also the person who’s on these supplements when that’s probably not the person who needs it,” he adds.

Just as home fertility tests for women have become increasingly available, brands are offering versions for men. Bird&Be’s At-Home Sperm Test checks for key variables like concentration and motility, then gives you a score. “We wouldn’t consider it diagnostic, but investigative, like a screening tool,” says Nayot. It’s these home tests that are, to Schlegel, an exciting advancement for men’s fertility. “Men don’t go see doctors as effectively or as often as women do, so the availability and technology behind some of these home testing kits has driven more men to be tested earlier,” he says.