Effects of Cumulative Duration of Repeated Anesthesia Exposure on Fetal Brain Development in the Ovine Model

( J Clin Anesth. 2023;85:111050. https://doi.org/10.1016/j.jclinane.2022.111050) During nonobstetric surgeries, general anesthesia is necessary in ∼1% of pregnant women. In a recent population cohort, 91% of these women underwent a single anesthesia exposure, averaging 89 minutes. However, 9% experienced multiple exposures. The duration of anesthesia varied: 29% had less than an hour, 49% had 1 to 2 hours, 12% had 2 to 3 hours, 6% had 3 to 5 hours, and 2% had 7 to 13 hours. The FDA issued a warning about potential fetal brain development impairment from repeated or prolonged anesthesia exposure (>3 h). A meta-analysis confirmed that in laboratory animals, repeated or prolonged exposure to general anesthesia results in neuronal injury and neurobehavioral impairments in fetuses. Short exposures (≤3 h) to ≤1 MAC of volatile anesthetics did not show significant neurodevelopmental impairments. Most studies were conducted in mice and rats, whose short gestation periods limit direct human comparisons. The 3-hour exposure in rodents equates to 40 to 47 hours in humans. A recent clinical study found no general population evidence linking prenatal anesthesia exposure to impaired neurodevelopment, though small sample sizes limited findings on prolonged exposure effects.