Unveiling the Outcomes of Mpox in Pregnancy: A Systematic Review and Single-Arm Meta-Analysis

The global resurgence of mpox, formerly monkeypox, poses an emerging threat to pregnant women due to immunological changes and potential vertical transmission, yet its impact on pregnancy remains underexplored. This study aims to pioneer a comprehensive assessment of pregnancy outcomes and the risks of vertical transmission associated with mpox infection during pregnancy.

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we searched three databases up to September 2024 for studies on pregnant women with mpox confirmed by quantitative polymerase chain reaction. Primary outcomes were composite adverse pregnancy outcomes: miscarriage or fetal death, congenital anomalies, and chorioamnionitis; the secondary outcome was vertical transmission. Study quality was assessed using Joanna Briggs Institute tools. Statistical analysis employed R software using a one-proportion model with Freeman-Tukey transformation and random-effects meta-analysis (restricted maximum-likelihood estimator, Knapp-Hartung adjustment), presenting estimated proportions with 95% confidence intervals (CIs).

Six studies (three case series, three case reports) comprising 11 singleton pregnancies were included. Diagnoses occurred in the first (27.3%), second (45.4%), and third trimesters (27.3%). Among the five genotypically identified Mpox cases, 20.0% were classified Clade I and 80.0% as Clade II. Meta-analysis indicated that an estimated 63% (95% CI, 43-83%) of pregnancies experienced composite adverse pregnancy outcomes. Specifically, miscarriage or fetal death occurred in 62% (95% CI, 21-102%), congenital anomalies in 50% (95% CI, 21-80%), and chorioamnionitis in 78% (95% CI, 44-96%). Vertical transmission was observed in 79% (95% CI, 6-151%). Despite small sample sizes leading to wide confidence intervals, high estimated proportions suggest that mpox severely impacts pregnancy outcomes, likely linked to maternal inflammation, placental invasion, and significant fetal risks from vertical transmission.

Mpox infection during pregnancy appears to be associated with high rates of adverse pregnancy outcomes and vertical transmission. Further large-scale studies are warranted to confirm these findings and develop preventive and management strategies mitigating this emerging threat.