Maternal Chikungunya virus infection and pregnancy outcomes: a global systematic review and meta-analysis of vertical transmission dynamics and associated morbidity.

Chikungunya virus (CHIKV) infection during pregnancy presents a major threat to maternal-fetal health, yet a comprehensive global assessment of vertical transmission risks and perinatal outcomes remains scarce. To provide a comprehensive evidence synthesis, we conducted a systematic review and meta-analysis, prospectively registered in PROSPERO (CRD420251164423). We screened studies published up to October 20, 2025, and included 57 observational studies for qualitative synthesis, with 27 studies pooled in meta-analyses. The pooled vertical transmission rate was 18.1%, revealing a pronounced gestational-age gradient: rates were low in the first (3.9%) and second (1.2%) trimesters but surged dramatically during the third trimester (36.5%) and the intrapartum period (49.1%). Adverse pregnancy outcomes occurred in 11.3% of infected women, with abnormal fetal heart rate (44.9%) and stillbirth (22.0%) being the most frequent. Among neonates, 36.5% experienced adverse outcomes, commonly including feeding difficulties (79.4%), fever (68.9%), and thrombocytopenia (57.2%); neonatal mortality reached 6.9%. Crucially, meta-analysis of comparative studies demonstrated that maternal CHIKV infection was associated with a more than two-fold higher risk of adverse perinatal outcomes (OR = 2.28), with particularly robust associations identified for abnormal fetal heart rate (OR = 5.07) and delayed neurodevelopment (OR = 11.98). This study underscores that maternal CHIKV infection, especially during late gestation, substantially elevates the risks of vertical transmission and severe perinatal complications. Consequently, our findings strongly advocate for the implementation of enhanced prenatal surveillance and systematic postnatal assessment protocols in CHIKV-endemic regions to mitigate adverse outcomes and guide public health interventions.