Pregnancy changes the variability of brain signaling

We have shown that pregnancy alters brain structure and brain activity, yet its effects on neural dynamics are unknown. This is the first study to investigate the effects of becoming a mother on neural variability, a measure of moment-to-moment fluctuations in brain activity. Longitudinal resting-state functional magnetic resonance imaging data were analyzed of 110 women participating in a prospective pre-conception study, including first-time mothers, second-time mothers and nulliparous control women. Significant differences were observed when comparing pre-to-post pregnancy variability changes in first-time mothers and second-time mothers to those in control women. Control women exhibited widespread reductions in neural variability across all neural networks over time, a pattern that may reflect normative aging and test-retest effects. In contrast, both first-time and second-time mothers showed relative stability in neural variability, diverging from the trajectory observed in controls. Notably, higher neural variability was associated with younger age across all groups, and age was positively associated with changes in attention and frontoparietal networks in first-time mothers. These findings show that pregnancy renders changes in the temporal dynamics of brain activity. Furthermore, becoming a mother alters the trajectory of reductions in neural variability typical for repeated scanning sessions and aging, suggesting compensatory neural adaptations.