Background
Understanding the size, gender composition, and cadre mix of the health workforce and how it has evolved across time and locations can inform policies for planning, recruitment, training, and retention of human resources for health (HRH), and improvement of access to the health-care workforce among populations. Using comparable and standardised data sources, we aim to describe the composition and density of health workers by sex among 20 cadres for 204 countries and territories over 1990–2023 and quantify workforce shortfalls relative to universal health coverage (UHC) attainment.

Methods
We used 1816 country-years of data from population-based surveys, 82 from censuses, 3888 from administrative sources, and 96 from scientific literature. We harmonised reported occupation in all sources with the International Standard Classification of Occupations 2008. We produced estimates for 20 cadres and the total health workforce disaggregated by sex using spatiotemporal Gaussian process regression, a standardised method in the Global Burden of Diseases, Injuries, and Risk Factors study. Finally, stochastic frontier meta-regression was used to estimate the minimum density of doctors, nurses and midwives, dentists, and pharmacists required to reach a score of 80 out of 100 on the UHC effective coverage index.

Findings
In 2023, there were 122·1 million (95% uncertainty interval 115·4–130·5) health workers across 20 cadres, an increase of 81·2 million (72·0–90·5) or 198·5% (161·9–245·6) relative to 1990. Of that total, there were 15·1 million (13·1–18·2) doctors, 33·2 million (30·8–36·3) nurses, 2·4 million (2·0–2·9) midwives, and 7·6 million (6·7–8·6) community health workers (CHWs). 68·9% (66·9–70·6) of all health workers in 2023 were female, and female health workers accounted for 71·4% (64·5–77·4) of net HRH workforce growth. Less than half of doctors were female (43·9%, 34·5–53·2) and most nurses (80·7%, 76·2–83·1), midwives (96·0%, 83·9–98·5), and CHWs (89·5%, 83·6–93·7) were female. Substantial differences in HRH density remained into 2023: sub-Saharan Africa had the lowest HRH densities across cadres, with the exception of CHWs, while high-income countries had the highest HRH densities. To reach 80 out of 100 on the UHC index, an additional 7·1 million (6·6–7·5) doctors, 23·9 million (21·8–26·1) nurses and midwives, 1·8 million (1·6–1·9) dentists, and 1·6 million (1·4–1·9) pharmacists are required globally.

Interpretation
The global health workforce has expanded substantially since 1990, largely due to women entering the formal health workforce. However, this expansion has been uneven across regions and persistent shortfalls remain in doctors, nurses and midwives, dentists, and pharmacists relative to moderate UHC attainment. Addressing these gaps will require expansion of training capacity, retention and remuneration policies for early-career workers, and gender-responsive workforce arrangements.