Medicines Use Research Group, Department of Clinical Pharmacology and Therapeutics, University of Malta, Msida, Malta.
Department of Paediatrics, Medical School, Mater Dei Hospital, Malta.
Early Hum Dev. 2020 Jan;140:104865. doi: 10.1016/j.earlhumdev.2019.104865. Epub 2019 Sep 3.
The sex ratio at birth has been studied for decades. A systematic review of the factors that influence this has never been performed. This study conducted a systematic search of this topic.
A scoping review of the literature was initially carried out in January 2012 and this was formally updated for contemporaneity in December 2017. A systematic search of the literature subsequently followed in May 2019 and was conducted based on PRISMA statement's flow diagram. The search was applied across five databases: Cumulative Index to Nursing and Allied Health Literature (CINAHL), MEDLINE, PubMed, The Cochrane Library and Web of Science and was restricted to January 1, 1990 to May 31, 2019. The systematic review stopped at screening stage of the PRISMA. A narrative approach was adopted to report study findings.
494 studies were included. Ten factors were identified from the literature as having an influence on M/F, with stress and sex-selective termination being the most predominant. Additional factors included the hormonal theory, geographical trends, coital rates, radiation, secular trends, seasonality and theoretical modeling.
Future studies addressing M/F should adopt similar methodologies in order to provide the possibility of comparison between findings and a more formal form of systematic review.
多年来，人们一直在研究出生性别比。目前还从未对影响这一比例的因素进行过系统的综述。本研究对这一主题进行了系统的文献检索。
2012 年 1 月首次进行了文献综述范围的评估，并于 2017 年 12 月根据 PRISMA 声明的流程图对其进行了更新。随后于 2019 年 5 月进行了系统的文献检索，该检索基于以下五个数据库进行：Cumulative Index to Nursing and Allied Health Literature (CINAHL)、MEDLINE、PubMed、The Cochrane Library 和 Web of Science，并将检索时间限制在 1990 年 1 月 1 日至 2019 年 5 月 31 日。该系统综述在 PRISMA 的筛选阶段停止。采用叙述性方法报告研究结果。
共纳入 494 项研究。文献中确定了 10 个对 M/F 有影响的因素，其中压力和性别选择性终止妊娠最为突出。其他因素包括激素理论、地理趋势、性交频率、辐射、世俗趋势、季节性和理论模型。
未来研究性别比应采用类似的方法，以便有可能对研究结果进行比较，并进行更正式的系统评价。
