Immune Checkpoint Inhibitor Exposure During Pregnancy: A Systematic Review

Immune checkpoint inhibitors (ICIs) have been widely implemented in current oncology practice. However, there is limited data regarding ICI administration in pregnancy. This systematic review aims to evaluate the risk-benefit of ICI exposure in pregnant women. We conducted searches in databases including PubMed, Scopus, Web of Science, and Embase from January 1, 2011 through April 30, 2025. Included studies were those that involved women with a cancer diagnosis who received ICI treatment while pregnant and had clinical findings of the fetus post-ICI treatment. Methodological quality and potential sources of bias were assessed using Joanna Briggs Institute Critical Appraisal Tools. The search generated 2539 citations. After removal of 696 duplicates, a total of 1843 citations were screened. Twenty case reports and three retrospective studies were included in the systematic review. Fetal complications and fetal immune-related adverse events among the case reports were at 23% and 11.5%, respectively. Preterm delivery occurred in 54% of case reports, and no fetal mortalities were reported. Regarding the observational studies, preterm delivery occurred in 20.9%-25.5% of cases, fetal mortality occurred in 2.2%-15.3% of cases, intrauterine growth restriction occurred in 6.5%-7.1% of cases, and complications attributable to prematurity were reported in 2.6%-5.5% of cases. The data from this systematic review suggests that the risk for fetal complications may be lower than previously reported. As ICIs continue to expand their role in the treatment of malignancy, their use in pregnancy is more likely to come into clinical question. Clinicians should approach ICI use in pregnancy with individualized, multi-disciplinary risk-benefit discussions.