Measles in pregnant women: A systematic review of clinical outcomes and a meta-analysis of antibodies seroprevalence

Objectives: Pregnant women represent a category at high risk of severe measles infection, that negatively affects the fetus as well. A systematic review of clinical outcomes of measles infection in gravid subjects and a meta-analysis of antibodies prevalence among pregnant women was conducted. Methods: MEDLINE and EMBASE databases were searched up to 18 June 2018. The screening focused on: (i) articles describing the outcome of measles in pregnancy, synthesized in a descriptive fashion; (ii) articles addressing the measles seroprevalence in cohorts of gravid women, analysed quantitatively. Results: Twenty-nine articles met inclusion criteria. A total of 420 cases of measles in gravid subjects were described, from 1941 to 2012. Among women, 18 deaths (4.3%) occurred, and the most frequent complication was pneumonia (75/420, 17.9%). Prematurity was the most important complication concerning fetal outcomes (55 out of 410 cases with available data, 13.4%). The random-effects pooled seroprevalence of measles in 20,546 gravid women worldwide was 89.3% (95% CI: 87.3-91.1%), that decreased, although not in a statistically significant way, over time (p = 0.54). Conclusions: Measles infection in pregnancy is dangerous both for the mother and the foetus. Antibody seroprevalence among gravid women on a global scale is lower than the herd immunity threshold.