BACKGROUND: There is a global shortage of midwives, whose services are essential to meet the healthcare needs of pregnant women and newborns. Evidence suggests that if enough midwives, trained and regulated to global standards, were deployed worldwide, maternal, and perinatal mortality would decline significantly. Health workforce planning estimates the number of midwives needed to achieve population coverage of midwifery interventions. However, to provide a valid measure of midwifery care coverage, an indicator must consider not only the raw number of midwives, but also their scope and competency. The tasks midwives are authorized to deliver and their competency to perform essential skills and behaviors provide crucial information for understanding the availability of safe, high-quality midwifery services. Without reliable estimates for an adequate midwifery workforce, progress toward ending preventable maternal and perinatal mortality will continue to be uneven. The International Labor Organization (ILO) and the International Confederation of Midwives (ICM) suggest standards for midwifery scope of practice and competencies. This paper compares national midwifery regulations, scope, and competencies in three countries to the ILO and ICM standards to validate measures of midwife density. We also assess midwives' self-reported skills/behaviors from the ICM competencies and their acquisition. METHODS AND FINDINGS: We compared midwives' scope of practice in Argentina, Ghana, and India to the ILO Tasks and ICM Essential Competencies for Midwifery Practice. We compared midwives self-reported skills/behaviors with the ICM Competencies. Univariate and bivariate analysis was conducted to describe the association between midwives' skills and selected characteristics. National scopes of practice matched two ILO tasks in Argentina, four in India, and all in Ghana. National standards partially reflected ICM skills in Categories 2, 3, and 4 (pre-pregnancy and antenatal care; care during labor and birth; and ongoing care of women and newborns, respectively) in Argentina (range 11% to 67%), mostly in India (range 74% to 100%) and completely in Ghana (100% match). 1,266 midwives surveyed reported considerable variation in competency for skills and behaviors across ICM Category 2, 3, and 4. Most midwives reported matching skills and behaviors around labor and childbirth (Category 2). Higher proportions of midwives reported gaining basic skills through in-service training and on-job-experience than in pre-service training. CONCLUSION: Estimating the density of midwives needed for an adequate midwifery workforce capable of providing effective population coverage is predicated on a valid numerator. A reliable and valid count of midwives to meet population needs assumes that each midwife counted has the authority to exercise the same behaviors and reflects the ability to perform them with comparable competency. Our results demonstrate variation in midwifery scopes of practice and self-reported competencies in comparison to global standards that pose a threat to the reliability and validity of the numerator in measures of midwife density, and suggest the potential for expanded authorization and improved education and training to meet global reference standards for midwifery practice has not been fully realized. Although the universally recognized standard, this study demonstrates that the complex, composite descriptions of skills and behaviors in the ICM competencies make them difficult to use as benchmark measures with any precision, as they are not defined or structured to serve as valid measures for assessing workforce competency. A simplified, content-validated measurement system is needed to facilitate evaluation of the competency of the midwifery workforce.