Background: Preeclampsia is a relatively frequent condition during pregnancy and childbirth. The administration of magnesium sulphate as a prophylactic and treatment measure is an evidence-based practice for eclampsia; however, it is not consistently used, compromising the health of pregnant women. This study aimed to assess compliance with recommendations of the International Society for the Study of Hypertension in Pregnancy (ISSHP) for the use of MgSO 4 in pregnant women with preeclampsia, before and after the implementation of the World Health Organization Safe Childbirth Checklist (SCC). Methods: This quasi-experimental study was conducted between July 2015 and July 2016 at a third-level maternity hospital in northeastern Brazil, where the SCC was implemented. Compliance (underuse and overuse of MgSO 4) was assessed in biweekly samples of 30 deliveries assessed 6 months before and 6 months after SCC implementation, using indicators based on international guidelines. A total of 720 deliveries were assessed over 1 year using an ad hoc application for reviewing medical records. Aggregated adequate use was estimated for the study period, and the time series measurements were compared to a control chart to assess change. Results: The incidence of preeclampsia was 39.9% (287/720). Among these, 64.8% (186/287) had severe signs or symptoms and needed MgSO 4. Underuse (no prescription when needed) of MgSO 4 was observed in 74.7% (139/ 186) of women who needed the drug. Considering all women, non-compliance with the prescription protocol (underuse and overuse) was 20.0% (144/720). After introducing the SCC, the use of MgSO 4 in women with preeclampsia with severe features increased from 19.1 to 34.2% (p = 0.025). Longitudinal analysis showed a significant (p < 0.05) ascending curve of adequate use of MgSO 4 after the SCC was implemented.