Incidence of Adverse Drug Reactions in High-Risk Pregnancy: A Prospective Cohort Study in Obstetric Intensive Care

Purpose To estimate the cumulative incidence of adverse drug reactions (ADRs) in women with high-risk pregnancy hospitalized in an obstetric intensive care unit, then to describe the medicines involved and to identify major risk factors. Methods From June 2016 to December 2017, patients admitted to the ICU with high-risk pregnancy were considered eligible in this observational, longitudinal, prospective study. Patients were investigated daily for the occurrence of ADRs through pharmaceutical anamnesis, active search in medical records and questioning of the health team. Suspected ADRs were classified according to Naranjo's algorithm. Written informed consent was obtained from all patients. Univariate and multivariate logistic regression were used to identify risk factors of ADR. Results The study population consisted of 607 high-risk pregnancies from 851 women admitted to the ICU, of whom 244 admitted for non-obstetric conditions, with an ICU stay less than 24 h or readmitted to the ICU were excluded. The mean age was 27.0 +/- 7.5 years-old, mean gestational age was 33.8 +/- 6.3 weeks. ADR were observed in 165 women (27.2%). No severe ADR was observed and 29.7% were of moderate severity. The most often implicated medicine was magnesium sulphate (25.2%) with 44.5% of patients administered that substance experiencing ADRs consisting of somnolence (68.6%), absent patellar reflex (21.6%) and hypotension (9.8%). Risk factors of ADR were blood pressure (adjusted odds-ratio (aOR) 1.02), haemoglobin level (aOR 1.21) and body temperature (aOR 0.71). Conclusions ADRs affect about one third of high-risk pregnancies, mainly due to magnesium sulphate administrations. High blood pressure, lower body temperature, and high haemoglobin concentration on admission were associated with an increased risk of ADR.