Asthma is common among women of childbearing and childrearing age. As a primary health care provider, the certified nurse-midwife is often called upon to play a direct role in diagnosis and collaborative co-management. This article reviews the pathogenesis of asthma and its natural history during pregnancy. Patient symptoms and findings on physical examination are described in depth, enabling clinicians to detect subtle presentations and avoid common pitfalls. A section on pulmonary function tests and other laboratory tools provides a foundation for objective monitoring of pulmonary function. Environmental control measures and pharmacologic therapies are described in detail. An algorithm for treatment strategies allows certified nurse-midwives to play an active role in co-management of their asthmatic patients, while a section on patient education highlights the essential teaching points her clients will require. Specific issues regarding antenatal fetal well-being and intrapartal management are discussed. With a sound knowledge base, and through their expertise in client education and counseling, the certified nurse-midwife is in a special position to optimize care for women with asthma.