Highly Sensitive Search String for Systematic Reviews and Meta-analyses Published in the top 20 Pregnancy and Childbirth Journals

This search string was designed to retrieve Systematic Reviews and Meta-analyses published in the top 20 Pregnancy and Childbirth Journals between January 1, 2007 and December 31st, 2015.本检索字符串旨在检索2007年1月1日至2015年12月31日期间，发表于前20种妊娠与分娩领域期刊的系统综述（Systematic Review）与Meta分析（Meta-analysis）。