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Review
. 2020 Mar 11;8(1):124.
doi: 10.3390/vaccines8010124.

Safety of Administering Live Vaccines During Pregnancy: A Systematic Review and Meta-Analysis of Pregnancy Outcomes

Almudena Laris-González  1   2 , Daniel Bernal-Serrano  2   3   4 , Alexander Jarde  5 , Beate Kampmann  6   7
Affiliations
Review

Safety of Administering Live Vaccines During Pregnancy: A Systematic Review and Meta-Analysis of Pregnancy Outcomes

Almudena Laris-González et al. Vaccines (Basel). .

Abstract

Live-attenuated vaccines (LAV) are currently contraindicated during pregnancy, given uncertain safety records for the mother-infant pair. LAV might, however, play an important role to protect them against serious emerging diseases, such as Ebola and Lassa fever. For this systematic review we searched relevant databases to identify studies published up to November 2019. Controlled observational studies reporting pregnancy outcomes after maternal immunization with LAV were included. The ROBINS-I tool was used to assess risk of bias. Pooled odds ratios (OR) were obtained under a random-effects model. Of 2831 studies identified, fifteen fulfilled inclusion criteria. Smallpox, rubella, poliovirus, yellow fever and dengue vaccines were assessed in these studies. No association was found between vaccination and miscarriage (OR 0.98, 95% CI 0.87-1.10), stillbirth (OR 1.04, 95% CI 0.74-1.48), malformations (OR 1.09, 95% CI 0.98-1.21), prematurity (OR 0.99, 95% CI 0.90-1.08) or neonatal death (OR 1.06, 95% CI 0.68-1.65) overall. However, increased odds of malformations (OR 1.24; 95% CI 1.03-1.49) and miscarriage after first trimester immunization (OR 4.82; 95% CI 2.38-9.77) was found for smallpox vaccine. Thus, we did not find evidence of harm related to LAV other than smallpox with regards to pregnancy outcomes, but quality of evidence was very low. Overall risks appear to be small and have to be balanced against potential benefits for the mother-infant pair.

Keywords: live attenuated vaccines; pregnancy outcomes; pregnant women; safety.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flowchart showing the study selection process for the qualitative and quantitative synthesis.
Figure 2
Figure 2
Meta-analysis of the association between maternal immunization and miscarriage. Forest plots showing the effect of vaccination during pregnancy on the odds of miscarriage in all trimesters (a) and in the first trimester (b), subgrouped by vaccine.
Figure 3
Figure 3
Meta-analysis of the association between maternal immunization and stillbirth. Forest plot showing the effect of immunization during pregnancy on the odds of stillbirth, subgrouped by vaccine.
Figure 4
Figure 4
Meta-analysis of the association of maternal immunization with congenital anomalies. Forest plots showing the effect of immunization during pregnancy on the odds of congenital anomalies in all trimesters (a) and in the first trimester (b), subgrouped by vaccine.
See this image and copyright information in PMC

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