(Update of a) systematic review on the impact of elective early term (< 39th gestational week) caesarean sections on maternal and neonatal health - a protocol.

Background: The rate of caesarean sections increased in the last decades to about 30% of births in western populations. Many caesarean sections are electively planned without an urgent medical reason for mother or child. Especially in women with a foregoing caesarean section, the procedure is planned early. An early caesarean section though may harm the newborn. Our aim is to evaluate the gestational time point after the 37th gestational week (after prematurity = term) of performing an elective caesarean section with the lowest morbidity for mother and child. Methods: This is an update of a systematic review previously carried out on behalf of the German Federal Ministry of Health. We will perform a systematic literature search in MEDLINE, EMBASE, CENTRAL and CINAHL. Our primary outcome is the rate of admissions to the neonatal intensive care unit in early versus late term neonates. We will include (quasi) randomized controlled trials and cohort studies. The studies should include pregnant women who have an elective caesarean section at term. We will screen titles and abstracts and the identified full texts of studies for eligibility. Risk of bias will be assessed with the Cochrane Risk of Bias Tool for Randomized Trials or with the Risk of Bias Tool for Non-Randomized Studies of Interventions (ROBINS-I). These tasks will be performed independently by two reviewers. Data will be extracted in beforehand piloted extraction tables. A dose-response meta-analysis will be performed. Discussion: Our aim is to reach a higher validity in the assessment of the time point of elective caesarean sections by performing a meta-analysis to support recommendations for clinical practice. We assume to identify less randomized controlled trials but a large number of cohort studies analyzing the given question. We will discuss similarities and differences in included studies as well as methodological strengths and weaknesses. Systematic review registration: PROSPERO <ext-link>CRD42017078231</ext-link> [ABSTRACT FROM AUTHOR]