BACKGROUND: WHO recommends prompt diagnosis and quinine plus clindamycin for treatment of uncomplicated malaria in the first trimester and artemisinin-based combination therapies in subsequent trimesters. We undertook a systematic review of women's access to and healthcare provider adherence to WHO case management policy for malaria in pregnant women. METHODS AND FINDINGS: We searched the Malaria in Pregnancy Library, the Global Health Database, and the International Network for the Rational Use of Drugs Bibliography from 1 January 2006 to 3 April 2014, without language restriction. Data were appraised for quality and content. Frequencies of women's and healthcare providers' practices were explored using narrative synthesis and random effect meta-analysis. Barriers to women's access and providers' adherence to policy were explored by content analysis using NVivo. Determinants of women's access and providers' case management practices were extracted and compared across studies. We did not perform a meta-ethnography. Thirty-seven studies were included, conducted in Africa (30), Asia (4), Yemen (1), and Brazil (2). One- to three-quarters of women reported malaria episodes during pregnancy, of whom treatment was sought by >85%. Barriers to access among women included poor knowledge of drug safety, prohibitive costs, and self-treatment practices, used by 5%-40% of women. Determinants of women's treatment-seeking behaviour were education and previous experience of miscarriage and antenatal care. Healthcare provider reliance on clinical diagnosis and poor adherence to treatment policy, especially in first versus other trimesters (28%, 95% CI 14%-47%, versus 72%, 95% CI 39%-91%, p = 0.02), was consistently reported. Prescribing practices were driven by concerns over side effects and drug safety, patient preference, drug availability, and cost. Determinants of provider practices were access to training and facility type (public versus private). Findings were limited by the availability, quality, scope, and methodological inconsistencies of the included studies. CONCLUSIONS: A systematic assessment of the extent of substandard case management practices of malaria in pregnancy is required, as well as quality improvement interventions that reach all providers administering antimalarial drugs in the community. Pregnant women need access to information on which anti-malarial drugs are safe to use at different stages of pregnancy. Please see later in the article for the Editors' Summary.