Abstract: The aim of the study was to discern if Sudden Infant Death Syndrome (SIDS) reflects a transient vulnerability to stimuli during anomalous ontogeny of normal cellular interaction within brain stem structures such as the parasolitary (Psol) nucleus. Perinatal exposure equivalent to the strength and frequency of a magnetic field configuration correlated with SIDS was utilized to produce alterations in cellular asymmetry within the Psol nucleus. The numbers of neurons and nuclei of astroglia and oligodendroglia from n = 40, 5 and 15 day old rats that had been exposed to a 0.5 Hz, 5 to 10 nT magnetic field between -3 to +7 days of birth and were counted at 1000 X. A robust and significant interaction (explaining 30% of the variance) between numbers of astroglia nuclei in the right vs. the left side of the nucleus, age and exposure to the field was demonstrated. These results indicate exposure to this specific intensity and frequency may delay the normal ontogeny of asymmetry-to-symmetry in cell numbers that affect the blood brain barrier and neuronal function. Greater attention to neuroaxial asymmetry in post-mortem measures of SIDS cases may be warranted.