Microcephaly Prevalence in Infants Born to Zika Virus-Infected Women: A Systematic Review and Meta-Analysis

Abstract

Zika virus is an emergent flavivirus transmitted by Aedes genus mosquitoes that recently reached the Americas and was soon implicated in an increase of microcephaly incidence. The objective of the present study is to systematically review the published data and perform a meta-analysis to estimate the prevalence of microcephaly in babies born to Zika virus-infected women during pregnancy. We searched PubMed and Cochrane databases, included cohort studies, and excluded case reports and case series publications. We extracted sample sizes and the number of microcephaly cases from eight studies, which permitted a calculation of prevalence rates that are pooled in a random-effects model meta-analysis. We estimated the prevalence of microcephaly of 2.3% (95% CI = 1.0–5.3%) among all pregnancies. Limitations include mixed samples of women infected at different pregnancy times, since it is known that infection at the first trimester is associated with higher risk to congenital anomalies. The estimates are deceptively low, given the devastating impact the infection causes over children and their families. We hope our study contributes to public health knowledge to fight Zika virus epidemics to protect mothers and their newborns.

Association of past dengue fever epidemics with the risk of Zika microcephaly at the population level in Brazil

“…Even so, a robust analysis using secondary databases estimated a peak of 49.9 microcephaly cases per 10,000 live births in the NE region, whereas for the other regions the peak did not surpass 10 cases per 10,000 live births 6 . So far, microcephaly ratios as high as in the Brazilian NE region have not been described in any other region in the world that had undergone a Zika epidemic [7][8][9] . Several reasons for this discrepancy were suggested -poor data quality [10][11][12] , the unreliability of secondary data sources 13,14 , virus genetic variation 15 , socioeconomic factors 16 , dengue immunity profile of the population 17 , and women postponing pregnancy or having abortions [18][19][20] .…”

Trimester-specific Zika virus infection affects placental responses in women

“…In animal studies, ZIKV infection of immuno-compromised pregnant female mice resulted in premature fetal death [34]; ZIKV was found in the placenta in these mice, leading to active placental infection, apoptosis and vascular damage [34]. In humans, it is worth noting that the estimated prevalence of microcephaly in babies born to ZIKV-infected pregnant women was ∼2.3% [35]. This estimate, however, considers infections that have occurred in any of the three trimesters [35].…”

“…In humans, it is worth noting that the estimated prevalence of microcephaly in babies born to ZIKV-infected pregnant women was ∼2.3% [35]. This estimate, however, considers infections that have occurred in any of the three trimesters [35]. The likelihood of microcephaly is thought to be higher if ZIKV infection occurs during the first trimester [11].…”

Stagnant contraceptive sales after the Zika epidemic in Brazil

“…There is an association between birth defects in the offspring and Zika virus infection during pregnancy, now termed Zika virus syndrome, albeit the magnitude of the risk remains unclear [4]. The Brazilian Ministry of Health's advice to postpone pregnancy has its limitations, as almost 74% of the population depend on the national health system for their health care, including the provision of free contraception.…”