OBJECTIVE:Human T-lymphotropic virus 1 (HTLV-1) infection is endemic in western French Guiana and is associated with maternal morbidity and mortality. However, data on related obstetric and neonatal complications remain limited. This study evaluated temporal trends in the prevalence of HTLV-1 among pregnant women, and assessed associations with adverse obstetric and neonatal outcomes. METHODS:A retrospective, single-centre study was conducted at Western French Guiana Hospital Centre from 2013 to 2021, comparing HTLV-1-infected parturients with uninfected controls. Univariate and multivariate analyses were performed. RESULTS:Among 24,294 births, 402 were infected with HTLV-1 (prevalence 1.66%), with a decreasing trend over the study period. HTLV-1 infection was associated with higher rates of preterm birth (<37 weeks: 15% vs 11%; p = 0.04) and hypertensive disorders of pregnancy (12% vs 8%; p = 0.01). Multivariate analysis confirmed an independent association with preterm birth (odds ratio 1.55, 95% confidence interval 1.12-2.13; p = 0.007). Rates of fetal loss, postpartum complications, and low birth weight did not differ between HTLV-1-infected and uninfected women. Additionally, 4.1% of HTLV-1-infected women developed adult T-cell leukaemia/lymphoma or HTLV-1-associated myelopathy/tropical spastic paraparesis during pregnancy or the postpartum period. CONCLUSION:Although the prevalence of HTLV-1 among parturients in western French Guiana has declined progressively, it remains associated with substantial morbidity and independently increases the risk of preterm birth. Further studies are needed to confirm this association and elucidate the underlying mechanisms.