Association between hypertensive disorders and Bell's palsy in pregnancy: protocol for a systematic review and meta-analysis

Background Bell's palsy is an idiopathic peripheral nerve palsy involving the facial nerve. Pregnancy, diabetes mellitus and hypertension are the risk factors for Bell's palsy. However, the association between hypertensive disorders and Bell's palsy during pregnancy or the puerperium remains unclear. This systematic review will comprehensively summarise the literature and evaluate the association between Bell's palsy and hypertensive disorders during pregnancy or the puerperium. Methods and analysis Systematic searches of PubMed, MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials will be undertaken using prespecified search strategies. Observational studies (cross-sectional studies, cohort studies, case reports and series case reports) written in English that investigate the association between hypertensive disorders of late pregnancy and Bell's palsy during pregnancy or the puerperium will be included. Different authors will independently conduct the eligible study selection, perform data extraction and appraise the quality of included studies. Subgroup analysis will be carried out based on the age of pregnant women (<= 35 years old, >35 years old), parity (primipara, multipara) and fetus number (singleton or multiple-gestation pregnancy). Ethics and dissemination This review will be based on published literature, and thus there is no requirement for ethics approval. The results of this study will aid in the knowledge of the relationship between Bell's palsy during pregnancy or the puerperium and hypertensive disorders of late pregnancy. The results of this systematic review will be shared through publication in a peer-reviewed journal with good visibility for the field of obstetrics and presentations at academic conferences.