Ending Maternal Mortality Act of 2018 This bill amends the Public Health Service Act to require the Department of Health and Human Services to publish every two years a national plan to reduce the rate of preventable maternal mortality (maternal deaths that occur during or within 12 months of pregnancy). Each plan must address specific issues relating to maternal mortality and severe maternal morbidity (unexpected outcomes of labor and delivery that result in significant short- or long-term consequences to a woman's health), such as issues surrounding public awareness, at-risk populations and disparities, and quality of care.