Sudden unexpected deaths in infancy (SUDI) is defined as the unexpected death of an infant in the first year of life, including explained and unexplained death (SIDS). Risk factors, such as sleeping position and passive smoking, have been identified but few studies have addressed the influence of exposure to chemicals in the environment. Pesticides are ubiquitous but little is known about their impact on infant mortality. We conducted a systematic review of studies on SUDI and pesticide exposure present in the MEDLINE database in March 2024. We included epidemiological and toxicological studies on humans. We identified 92 studies in total, 17 of which were included in the analysis. Biases were assessed qualitatively and with the NTP/OHAT evaluation process. Epidemiological studies reported various results. Three studies found an association between SIDS and parental occupational exposure. Conflicting results were obtained in studies of domestic exposure, with half the studies showing no association. One accidental massive exposure to insecticides was associated with an increase in infant mortality. Several studies detected pesticides in brain samples from cases of SIDS, demonstrating exposure to organochlorine and organophosphate, and passage across the blood-brain barrier. Many of these studies were quite old and may therefore not be representative of current exposure levels. Case-control studies may be associated with recall bias or measurement errors. It is not possible to establish a clear association between SUDI and pesticide exposure from our findings. Further epidemiological studies are required. Studies on sudden perinatal deaths with universal definitions would be helpful.