Elevated risk of stillbirth in males : systematic review and meta-analysis of more than 30 million births

Mondal, D; Galloway, T; Bailey, T; Mathews, F

Abstract

Background: Stillbirth rates have changed little over the last decade, and a high proportion of cases are
unexplained. This meta-analysis examined whether there are inequalities in stillbirth risks according to sex.
Methods: A systematic review of the literature was conducted, and data were obtained on more than 30 million
birth outcomes reported in observational studies. The pooled relative risk of stillbirth was estimated using
random-effects models.
Results: The crude mean rate (stillbirths/1,000 total births) was 6.23 for males and 5.74 for females. The pooled
relative risk was 1.10 (95% confidence interval (CI): 1.07–1.13). The attributable fraction in the whole population was
4.2% (95% CI: 3.70–4.63), and the attributable fraction among male fetuses was 7.8% (95% CI: 7.0–8.66). Study
populations from countries with known sex-biased sex selection issues had anomalous stillbirth sex ratios and
higher overall stillbirth risks than other countries, reflecting increased mortality among females.
Conclusions: Risk of stillbirth in males is elevated by about 10%. The population-attributable risk is comparable
to smoking and equates to approximately 100,000 stillbirths per year globally. The pattern is consistent across
countries of varying incomes. Given current difficulties in reducing stillbirth rates, work to understand the causes of
excess male risk is warranted. We recommend that stillbirths are routinely recorded by sex. This will also assist in
exposing prenatal sex selection as elevated or equal risks of stillbirth in females would be readily apparent and
could therefore be used to trigger investigation.

Citation

Mondal, D., Galloway, T., Bailey, T., & Mathews, F. (2014). Elevated risk of stillbirth in males : systematic review and meta-analysis of more than 30 million births. BMC Medicine, 12(220), https://doi.org/10.1186/s12916-014-0220-4

• Journal Article Type: Article
• Acceptance Date: Oct 24, 2014
• Online Publication Date: Nov 27, 2014
• Publication Date: Dec 1, 2014
• Deposit Date: Jan 22, 2015
• Publicly Available Date: Apr 5, 2016
• Journal: BMC Medicine
• Electronic ISSN: 1741-7015
• Publisher: Springer Verlag
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Issue: 220
• DOI: https://doi.org/10.1186/s12916-014-0220-4
• Publisher URL: http://dx.doi.org/10.1186/s12916-014-0220-4
• Related Public URLs: http://www.biomedcentral.com/bmcmed/