Data extraction and quality assessment
Two authors independently extracted the data from all of the full articles included in the research. The specific format is as follows: I) General characteristics of study: study, year, number of participants, gestation age. II) Intervention: dosage and duration. III) Outcomes. All discrepancies in data interpretation are handled by discussion with third-party reviewers. If there are inconsistent results indicator units in the research, the units should be uniformly converted before subtask data processing.
Two researchers independently assessed the methodological quality of RCTs using the Cochrane Collaboration’s tool. Furthermore, after entering the evaluation data into the RevMan 5.4 software, the bias risk assessment chart could be obtained. Any disagreement was settled by a conversation with the third reviewer, and then the research was then reevaluated.