Maternal occupational risk factors and preterm birth: Protocol for a systematic review and meta-analysis

IntroductionPreterm birth, which accounts for 33.1% of neonatal death globally, is the main cause of under-five mortality. A growing number of studies indicate that occupational risk factors during pregnancy are linked to an increased likelihood of poor pregnancy outcomes. The effect of physical occupational risks on preterm birth has received very little attention, and previous reviews have produced inconclusive results. This systematic review aims to update the evidence on the relationship between maternal physical occupational risks and preterm birth.Method and analysisWe will search electronic databases including Ovid Medline, Embase, Emcare, CINAHL, Scopus, and Web of science to find peer-reviewed studies examining the relationship between six common maternal physical occupational risks (heavy lifting, prolonged standing, heavy physical exertion, long working hours, shift work, and whole-body vibrations) and preterm birth. Articles published in English after 1 January 2000 will be included without geographic restrictions. Two reviewers will screen titles and abstracts independently, and then select full-text articles that meet inclusion criteria. Methodological quality of the included studies will be evaluated using the Joanna Briggs Institute (JBI) critical appraisal method. The quality of evidence across each exposure and the outcome of interest will be examined by using the GRADE (Grade of Recommendations, Assessment, Development, Evaluation) method. Accordingly, a high level of evidence will lead to "strong recommendations". A moderate level of evidence will lead to "practice considerations". For all evidence levels below moderate, the message will be "not enough evidence from the scientific literature to guide policymakers, clinicians, and patients. If data permits, a meta-analysis will be conducted using Stata Software. In case where meta-analysis is not possible, we will perform a formal narrative synthesis.Discussion and conclusionEvidence suggests that preterm birth is linked to a number of maternal occupational risk factors. This systematic review will update, compile, and critically review the evidence on the effect of maternal physical occupational risk on preterm birth. This systematic review will provide guidance to support decision-makers including maternal and child health services, other health care providers, and government policy agencies.