Tiny Health

A baby's diaper, read like a medical chart

Somewhere in Austin right now, a parent is scooping a sample from a diaper into a small tube, sealing it, and mailing it to a lab. A week or two later they open an app and see, in plain language, which bacteria are thriving in their child's gut, which are missing, and what to do about it. That is the entire business in one sentence - and it took a long time to make it sound that simple.

Tiny Health sells at-home microbiome tests. Stool for the gut, a swab for the vaginal microbiome. The unfashionable part is what happens after the sample arrives: DNA sequencing, age-specific reference ranges, and a set of recommendations a tired parent can actually follow. By the end of 2025 the company had processed more than 100,000 tests and signed on over 3,000 health practitioners. What started as a curiosity for new parents now reaches all the way to longevity clinics.

The gut sets its course before age three

Here is the uncomfortable science Tiny Health is built around. A child's core gut microbiome is largely established in the first few years of life. Antibiotics, C-sections, formula, the family dog, the timing of solid foods - all of it nudges which microbes move in and stay. Get that window wrong and the research links it to eczema, allergies, asthma, and digestive trouble that can trail a person for decades.

For adults, the microbiome industry was already crowded with tests of varying seriousness. For babies, there was essentially nothing built for them. Pediatricians could order a clinical stool test for a specific infection, but no one was handing parents a map of their infant's whole microbial neighborhood while there was still time to change it. The problem was not a lack of demand. It was that the smallest, highest-stakes patients had been skipped.

A mother who couldn't find the test she needed

Cheryl Sew Hoy did not set out to start a microbiome company. A Cornell-trained engineer and serial entrepreneur, she became a mother and then a frustrated one - her child struggled with eczema, sleep, and food sensitivities, and the answers she got were vague. She went looking for a way to actually examine her infant's gut and found that the tool she wanted did not exist. So she built it.

The bet was not subtle: take the sequencing technology that research labs use, wrap it in age-specific science, and put it in the hands of parents at home. She founded Tiny Health in 2020 and spent two years on R&D before selling a single kit - assembling microbiologists, pediatric physicians, and an advisory bench that reads like a microbiome syllabus, including UCLA's Dr. Emeran Mayer and Johns Hopkins epidemiologist Noel Mueller. Dr. Elisa Song, a Stanford-trained integrative pediatrician, came on as Chief Medical Officer. The test launched in 2022.

Sequencing, then the part everyone skips

Plenty of companies will sequence a sample and hand you a colorful pie chart. Tiny Health's argument is that the chart is the easy part. Its tests run DNA sequencing against reference ranges tuned to the person's life stage - an infant gut is not a tiny adult gut - and then translate the results into specific, research-backed recommendations drawn from more than 1,500 reviewed papers. The product is the advice as much as the data.

Numbers that did the convincing

Skeptics are right to ask whether a consumer microbiome test is science or merchandise. Tiny Health's answer is a published randomized controlled trial in Pediatric Allergy and Immunology: among C-section infants, those who got Tiny Health's personalized microbiome support had 83% lower odds of developing eczema. That is a rare thing in this category - an actual trial behind the marketing.

The other number that raised eyebrows came from the vaginal microbiome data: 39% of women who sampled had low or absent Lactobacillus, a bacterium tied to fertility outcomes. It is the kind of finding that turns a product into a dataset - and a dataset is what attracted clinical partners. Mayo Clinic's Executive and Longevity Health Programs and the Pritikin Longevity Center have folded Tiny Health gut testing into preventive care.

Health, aimed at the people who can't ask for it yet

The stated mission is to improve the health outcomes of future generations through evidence-based microbiome insights. In practice that means starting earlier than almost anyone else - with patients who cannot describe their own symptoms - and refusing to treat the gut as a wellness accessory. Tiny Health is a direct-to-consumer business, but the thing it is actually selling is foresight.

That mission is now stretching in both directions. The company that began at birth is following its customers toward the other end of life, with a Microbiome Age research edition for adults over 60 and partnerships with longevity clinics. Same science, wider window. The pitch is consistent: see the imbalance while you can still do something about it.

The diaper, revisited

Pediatric chronic conditions - allergies, eczema, asthma, autoimmune trouble - have been climbing for a generation, and a lot of the suspected wiring runs through the gut. If even part of that can be spotted and nudged in the first years of life, the math is enormous: cheaper than a lifetime of managing a condition, and far kinder. That is the wager Tiny Health is running at scale, one mailed sample at a time.

So go back to that parent in Austin, sealing a tube over a changing table. A few years ago that gesture led nowhere - there was no test to send it to. Now it lands in a lab, gets read against the science of the first 1,000 days, and comes back as something a parent can use before the window closes. Tiny Health did not invent the microbiome. It just decided the smallest patients deserved to be looked at first - and then proved someone would do the looking.