Risks Associated With Smallpox Vaccination in Pregnancy

Abstract

Objective To estimate the maternal and fetal risks of smallpox vaccination during pregnancy. Data Sources MEDLINE, Web of Science, EMBASE, Global Health, ClinicalTrials.gov, and CINHAL from inception to September 2014. Methods of Study Selection 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). Tabulations, Integration, and Results 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. Conclusion 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.

General and reproductive health outcomes among female greenhouse workers: a comparative study

“…The primary infertility is defined as women who do not have experienced a pregnancy without using of contraception after 1 year of intercourse and secondary infertility refers to the inability of women for pregnancy after experience at least one pregnancy in the past [19]. Spontaneous abortion was considered as the ending of pregnancy before 20 weeks of gestation and stillbirth as death occurring after the 20th week of gestation [20]. Also, a newborn delivered before 37 weeks of gestation was considered as a preterm birth and a neonate delivered after 42 weeks of gestation was considered as a postterm labor [12].…”

Gebeli̇k Ve İmmuni̇zasyon

“…Gebelikte canlı aşısı kontrendike olduğundan, inaktif polisakkarid aşı (Tyiphim Vi) aşılama gerektiğinde uygulanabilmektedir [37].…”

Stillbirth: Case definition and guidelines for data collection, analysis, and presentation of maternal immunization safety data

“…However, there is some data available on stillbirth rates following immunization showing no safety concerns [84], [85], [86]. A meta-analysis of eleven studies reported data on stillbirth (defined as fetal death ≥20 weeks of gestation) and found that the smallpox vaccination is not associated with an increased risk of stillbirth, pooled RR 1.03 (95% CI: 0.75–1.40) [87]. A study conducted in Finland during a mass oral poliovirus immunization campaign conducted between 1984 and 1986 reported stillbirth rates among women who were pregnant during the period of vaccination and whose infants were delivered at the three major hospitals in the Helsinki area between 0.4% and 0.6%, depending on their trimester of exposure, compared with 0.45% in the reference cohort [88].…”