Danaher's first quarter delivered adjusted EPS up 9.5% to $2.06 ahead of expectations, with total core revenue roughly flat as a 2.5% respiratory headwind at Cepheid offset 3% growth elsewhere. Bioprocessing was a highlight, posting high-single-digit consumables growth, China strength, and the first positive equipment order growth in nearly two years at over 30%. Management reaffirmed its full-year outlook for core growth accelerating to mid-single digits by the fourth quarter and confirmed the pending Masimo acquisition is progressing toward a close later this year.
Good morning, everyone, and thanks for joining us on the call. With us today are Rainer Blair, our President and Chief Executive Officer, and Matt Gugino, our Executive Vice President and Chief Financial Officer. I'd like to point out that our earnings release, quarterly report on Form 10-Q, the slide presentation supplementing today's call, the reconciliations and other information required by SEC Regulation G relating to any non-GAAP financial measures provided during the call, and a note containing details of historical and anticipated future financial performance are all available on the investors section of our website, www.danaher.com, under the heading Quarterly Earnings. The audio portion of this call will be archived on the investors section of our website later today under the heading Events and Presentations and will remain archived until our next quarterly call. A replay of this call will be available until May 5, 2026.
During the presentation, we will describe certain of the more significant factors that impacted year-over-year performance. Our Form 10-Q and the supplemental materials I referenced describe additional factors that impacted year-over-year performance. Unless otherwise noted, all references in these remarks and supplemental materials to company-specific financial metrics relate to the first quarter of 2026, and all references to period-to-period increases or decreases in the financial metrics are year-over-year. We may also describe certain products and devices which have applications submitted and pending for certain regulatory approvals or are available only in certain markets. During the call, we will make forward-looking statements within the meaning of the Federal Securities Law, including statements regarding events or developments that we believe or anticipate will or may occur in the future.
These forward-looking statements are subject to a number of risks and uncertainties, including those set forth in our SEC filings, and actual results may differ materially from any forward-looking statements that we make today. These forward-looking statements speak only as of the date that they are made, and we do not assume any obligation to update any forward-looking statements except as required by law. With that, I'd like to turn the call over to Rainer.
Thank you, Rachel, and good morning, everyone. We appreciate you joining us on the call today. We're off to a solid start to the year. Our team executed well in a dynamic environment, leveraging the Danaher Business System to accelerate innovation, drive productivity gains, and deliver better than expected adjusted EPS growth. On the top line, continued strength in bioprocessing and better than expected performance in life sciences largely offset the impact of a lighter than normal Q1 respiratory season at Cepheid. Now, looking across the portfolio, trends in many of our end markets were modestly better than our expectations entering the year. In large pharma and biopharma, commercial monoclonal antibody production remained robust, and we continued to see gradual improvement in R&D spending. Trends at smaller biotech and academic and government customers were stable sequentially, with some pockets of improved order and funnel activity.
Meanwhile, clinical and applied end markets performed well, consistent with recent quarters. Geographically, we saw an acceleration in our life sciences and biotechnology businesses in China. Now, the global environment has become more dynamic since the start of the year, including the ongoing conflict in the Middle East. While we have limited direct revenue or supply chain exposure to the region, we're mindful of potential pressures from a sustained conflict. That said, we remain focused on controlling what we can control, including leveraging the Danaher Business System to proactively manage our supply chain and mitigate inflationary pressures while continuing to invest for the long term. At the same time, we're enhancing our portfolio through strategic M&A, including the pending acquisition of Masimo, where we believe there are significant opportunities to improve performance over time through DBS and our global scale.
With the strength of our balance sheet and robust free cash flow generation, we're well positioned for further capital deployment going forward. With that, let's take a closer look at our first quarter 2026 results. Sales were $6 billion in the first quarter, and core revenue was up 0.5% year-over-year, with a 2.5% headwind from respiratory revenue partially offsetting 3% core revenue growth in the rest of the business. Despite a lighter than typical Q1 respiratory season, underlying momentum across the portfolio improved as many end market headwinds began to moderate. Geographically, core revenue in developed markets were down slightly, with a mid-single-digit decline in North America and a mid-single-digit increase in Western Europe. High growth markets were up low single digits with solid performance across most regions, including mid-single digit growth in China.
In China, better than expected growth in biotechnology and life sciences more than offset the expected high single-digit decline in diagnostics, which continued to be impacted by volume-based procurement and reimbursement policy changes. Our gross profit margin for the first quarter was 60.3% and our adjusted operating profit margin of 30.2% was up 60 basis points, reflecting the benefit of year-over-year cost savings, more than offsetting the negative impact from lower respiratory revenue year-over-year. Adjusted diluted net earnings per common share of $2.06 were up 9.5% year-over-year. We generated $1.1 billion of free cash flow in the quarter, resulting in a free cash flow to net income conversion ratio of 105%.
Turning to capital deployment, in February, we announced our intention to acquire Masimo, a leading provider of mission critical pulse oximetry and patient monitoring solutions in acute care settings. We've followed Masimo for over a decade and believe the company is well-positioned with its trusted brand, differentiated technology, and attractive financial profile. Looking ahead, we believe there are clear opportunities to run the same playbook that has driven value creation across our portfolio for many years, leveraging DBS to drive growth and expand margins while further strengthening our value proposition with customers. We expect Masimo to be accretive to adjusted diluted net earnings per common share in the first full year post-acquisition, and to deliver high single digit return on invested capital by the fifth full year of our ownership.
The transaction remains subject to customary closing conditions, including regulatory approvals, and we look forward to welcoming the talented Masimo team to Danaher later this year. Now alongside M&A, we made significant progress on organic growth initiatives across Danaher, including new product introductions and strategic partnerships. These efforts are strengthening our competitive positioning while helping customers improve quality and yield, reduce costs, and accelerate the delivery of life-changing therapies and diagnostics. Let me highlight a few examples. In biotechnology, Cytiva launched Fibro dT, a next generation mRNA purification platform that improves manufacturing speed and efficiency. By eliminating diffusion limitations associated with traditional purification methods, Fibro dT reduces processing time, increases yield, and lowers material usage, enabling more cost-effective, higher throughput production of mRNA-based therapies. Additionally, Cytiva will showcase its next generation automated perfusion system, or APS, at the INTERPHEX trade show this week.
APS is a cutting-edge tangential flow filtration platform designed to address key challenges of currently available process intensification systems, including product loss, filter clogging, and scalability. In life sciences, Beckman Coulter Life Sciences announced a strategic partnership with Automata, combining its liquid handling, genomic, and cell analysis technologies with Automata's AI-ready automation platform. This partnership is positioned to empower scientists with AI-driven tools and automated workflows to improve throughput, workflow reliability, and data integrity in increasingly autonomous research environments. Beckman Coulter Diagnostics continued to make progress on menu expansion for the high-resolution DxI 9000 Immunoassay Analyzer with FDA clearance of the HBc IgM assay for acute hepatitis B. With this clearance, nearly all core blood virus assays for the DxI 9000 are now cleared in both the U.S. and the European Union.
This closes a historical gap in Beckman's immunoassay test menu and positions Beckman to accelerate new placements, customer wins, and growth as the DxI 9000 rollout continues. Now let's take a closer look at our results across the portfolio and give you some color on what we saw in our end markets. Core revenue in our biotechnology segment increased 7%. Core revenue in discovery and medical declined low single digits. Growth in medical filtration and research consumables was more than offset by declines in protein research instrumentation as academic customers continued to face funding constraints. Core revenue and bioprocessing grew high single digits in the first quarter. High single digit growth in consumables was driven by robust demand for commercialized therapies globally, with notable strength in China.
Equipment declined modestly in Q1, but we were encouraged to see orders growth of more than 30%, marking the first quarter of year-over-year equipment order growth in nearly two years. Stepping back on bioprocessing, monoclonal antibody production remains robust and is expected to continue growing at historical or better rates, driven by new molecules, biosimilars, and increased utilization of existing therapies. In fact, we saw a sustained pace of new biologic drug approvals in the first quarter of 2026, building on a robust level of approvals in 2025. At the same time, equipment investment has been relatively muted, which we believe creates a growing need for incremental capacity in the coming years. We're encouraged by improved trends in bioprocessing equipment and believe we're in the early stages of a multi-year investment cycle. We see activity in brownfield projects today with larger greenfield investments expected to follow.
Given Cytiva's expansive global footprint, broad portfolio, and depth of technical expertise, we're well positioned to benefit from this capacity expansion across biologic drug production. Turning to our Life Sciences segment, core revenues increased by 0.5%. Core revenue in our Life Sciences instruments businesses declined low single digits, primarily driven by weakness in North America academic research customers, as we expected. While demand at academic research customers remained muted in the quarter, we saw early signs of momentum building in our order book. We continue to see a gradual improvement in large pharma and biopharma investment. Instrumentation demand at biotech customers remained muted but stable, though we were encouraged to see recovery in the funding environment drive improved funnel activity. Core revenue in our Life Sciences consumables businesses collectively grew low single digits. Aldevron grew in the quarter, driven by solid commercial execution and an improved biotech funding environment.
We also saw early pockets of improvement in academic customers and research consumables contributing to growth at Abcam. We're particularly pleased by Abcam's recent performance, as DBS-driven commercial execution has gained traction and cost structure initiatives have driven meaningful margin expansion since acquisition. As end markets improve, we expect continued progress on both growth and margins at Abcam. Moving to our diagnostics segment, core revenue declined 4%. Core revenue in our clinical diagnostics businesses grew low single digits with mid-single digit growth outside of China. In China, pricing headwinds in the quarter from volume-based procurement and reimbursement policies were consistent with our expectations, and the anticipated impact from remaining policy changes remains consistent with our expectations from the start of the year.
At the same time, volume growth in China was slightly better than our expectations, an encouraging indicator for future demand and growth as we move past the most significant year-over-year impacts from current policy headwinds. Beckman Coulter Diagnostics delivered another strong quarter, with mid-single digit growth outside of China led by immunoassay reagents and instrumentation. In molecular diagnostics, Cepheid's revenue declined in the quarter as respiratory revenue was down approximately 25% year-over-year, given lower than typical seasonal respiratory infection rates. Cepheid's core non-respiratory test menu was up mid-teens, led by our 20% growth in sexual health and hospital-acquired infections assays. Now we've seen strong early demand and several notable customer wins for Cepheid's recently cleared Xpert GI Panel, a multiplex PCR test that quickly detects 11 common gastrointestinal pathogens from a single patient sample.
Thanks, Rainer. That concludes our formal comments. We're now ready for questions.