To estimate the maternal and fetal risks of smallpox vaccination during pregnancy.
MEDLINE, Web of Science, EMBASE, Global Health, ClinicalTrials.gov, and CINHAL from inception to September 2014.
We included published articles containing primary data regarding smallpox vaccination during pregnancy that reported maternal or fetal outcomes (spontaneous abortion, congenital defect, stillbirth, preterm birth, or fetal vaccinia).
The primary search yielded 887 articles. After hand-searching, 37 articles were included: 18 articles with fetal outcome data and 19 case reports of fetal vaccinia. Outcomes of smallpox vaccination in 12,201 pregnant women were included. Smallpox vaccination was not associated with an increased risk of spontaneous abortion (pooled relative risk [RR] 1.03, confidence interval [CI] 0.76-1.41), stillbirth (pooled RR 1.03, CI 0.75-1.40), or preterm birth (pooled RR 0.84, CI 0.62-1.15). When vaccination in any trimester was considered, smallpox vaccination was not associated with an increased risk of congenital defects (pooled RR 1.25, CI 0.99-1.56); however, first-trimester exposure was associated with an increased risk of congenital defects (2.4% compared with 1.5%, pooled RR 1.34, CI 1.02-1.77). No cases of fetal vaccinia were reported in the studies examining fetal outcomes; 21 cases of fetal vaccinia were identified in the literature, of which three neonates survived.
The overall risk associated with maternal smallpox vaccination appears low. No association between smallpox vaccination and spontaneous abortion, preterm birth, or stillbirth was identified. First-trimester vaccination was associated with a small increase in congenital defects, but the effect size was small and based on limited data. Fetal vaccinia appears to be a rare consequence of maternal smallpox vaccination but is associated with a high rate of fetal loss.
Pharmacology, Toxicology and Pharmaceutical Science
2
4%
Social Sciences
2
4%
Other
7
12%
Unknown
17
30%
Attention Score in Context
Attention Score in Context
This research output has an Altmetric Attention Score of 385. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 27 March 2023.
All research outputs
#96,020
of 32,202,065 outputs
Outputs from Obstetrics & Gynecology
#107
of 12,227 outputs
Outputs of similar age
#807
of 299,233 outputs
Outputs of similar age from Obstetrics & Gynecology
#4
of 163 outputs
Altmetric has tracked 32,202,065 research outputs across all sources so far. Compared to these this one has done particularly well and is in the 99th percentile: it's in the top 5% of all research outputs ever tracked by Altmetric.
So far Altmetric has tracked 12,227 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 20.3. This one has done particularly well, scoring higher than 99% of its peers.
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We're also able to compare this research output to 163 others from the same source and published within six weeks on either side of this one. This one has done particularly well, scoring higher than 97% of its contemporaries.
