Tiny Health Secures $33 Million Series B to Scale Infant Microbiome Testing and Clinician Partnerships

Cheryl Sew Hoy’s personal quest to understand her daughter’s eczema, allergies, and food sensitivities sparked a startup idea she didn’t anticipate: Tiny Health. After observing a stark contrast between her children—one born by cesarean delivery and the other vaginally—Sew Hoy wondered if early microbial exposure could influence health outcomes. Although she didn’t land a diagnosis, she found a path forward. “If you focus on a baby’s early life, you can course-correct by ensuring beneficial bacteria are present,” she recalls. When her son was born in 2020, she quickly formed Austin-based Tiny Health the following week. Now, the company has announced a $33 million Series B round led by B Capital, bringing total funding to $46 million since a 2021 seed and an August 2023 Series A. Existing backers Spero Ventures, The Venture City, and Overwater Ventures joined, with new investors Black Opal Ventures and Alumni Ventures also participating. B Capital’s Nick Whitehead will join Tiny Health’s board.

Tiny Health is riding growing demand for at‑home microbiome tests. The company reports that overall revenue has more than doubled year over year, with its B2B arm, Powered by Tiny—providing tests through healthcare providers and corporate partners—expanding fourfold last year. While Sew Hoy won’t disclose revenue or current valuation, she notes the Series B valuation is significantly higher than in the prior round. The company spent two years building its platform before launching an infant gut test in 2022, a move that gave Tiny Health a precise entry point into a market where anxious parents seek explanations and clinicians lack practical microbiome tools. Beyond infants, Tiny Health now offers tests for pregnancy, vaginal microbiome, and adults, with adults becoming the larger testing segment over time. Operationally, customers collect a small stool sample with a swab, send it back, and receive a report detailing detected microbes, their potential roles, and suggested next steps.

The Tiny Plus subscription couples a baseline test with retesting. A key differentiator, Sew Hoy says, is the use of shotgun metagenomic sequencing to analyze microbial DNA, providing a broader view than tests that target a limited set of organisms. Kimberley Sukhum, the chief science officer since 2021, leads the scientific work, while co-founder Donald Koo oversees technology and Dr. Elisa Song, a pediatrician, serves as chief medical officer. Reports include context about detected microbes and actionable guidance, linking to supporting research. “We’re a wellness test, not a diagnostic,” Sew Hoy emphasizes, stressing that results are designed to be actionable and evidence-backed. Although insurance rarely covers these tests, they enable users to gain insight into their gut microbiome and potential health influences. The field has other players with complementary approaches; for example, Throne Science in Austin has developed a toilet‑attached device to track stool patterns and hydration and recently raised $10 million in a Series A led by Will Ventures. Powered by Tiny remains the fastest-growing segment, enabling testing through healthcare providers and partner companies such as Superpower, Fullscript, and Mayo Clinic’s Executive Health and Longevity Programs.

Tiny Health also collaborates with supplement manufacturers and academic partners wanting to include microbiome data in clinical studies. Early adopters began sharing their results with clinicians, who increasingly request support in interpreting the findings. Today, Tiny Health serves more than 6,000 practitioners and offers clinician training to integrate its tests into patient care. Beyond direct consumer tests, Tiny Health’s enterprise efforts include technology integrations with various health and wellness brands. The company is expanding both its direct-to-consumer and enterprise footprints, along with clinician education, using the new funds. Whitehead of B Capital describes Tiny Health as uniquely positioned to translate microbiome science into practical consumer insights: “We’re at a pivotal moment when people want proactive health data, not just incident-driven care.” He notes that Tiny Health’s clinician involvement during diligence was strong and that its infancy data—nearly 200,000 microbiome samples—adds to its credibility. Looking ahead, Tiny Health plans to deploy roughly $5 million to grant researchers and clinical partners access to its testing and data, while continuing to build TinyAI, a tool that leverages its data and vetted research to interpret results.

The company envisions using microbiome pattern discovery to flag potential health risks before they manifest and to enable early interventions. Sew Hoy highlights four published scientific papers, including infant-focused research, with more studies planned to explore adult populations. With around 40 employees today, Tiny Health intends to hire about 30 more as it scales. The fresh capital will support expanded provider collaborations and additional research into whether microbiome modulation can improve health outcomes, alongside strategic investments in data infrastructure, education, and product development. Tiny Health’s mission remains to translate cutting-edge microbiome science into practical, evidence-based guidance for families and clinicians, aiming to redefine preventive health through the gut.