# Effect of Childbirth Experience on Cognitive Performance and Event-Related Potential Patterns
## 4 Discussion  
In this study, we evaluated the cognitive differences between porous and nulliparous females using the 3-back task and analyzed EEG data for electrophysiology. There were no differences between the two groups in terms of the correct answer rate or response time. In addition, there were no significant differences in terms of amplitude values of the N100, P300, P600, P300p_p, or P600p_p components at Fz, Cz, and Pz. To date, there have been no conclusive reports regarding the correlation between pregnancy/birth and cognitive abilities, i.e., whether pregnancy affects cognitive function and whether the effect persists after birth. In a previous study, women in their second trimester (13-26 weeks) tended to rate themselves as more cognitively impaired than before compared to nulliparous women, but the two groups did not differ in their performance on objective cognitive function tests [1]. Changes in memory are known to be primarily caused by complex hormonal changes during pregnancy, birth, or the postpartum period [3]. Oxytocin, which plays an integral part in labor by inducing powerful contractions of the uterus, is known to affect memory and cognitive performance, but no correlation between pregnancy-associated increases in oxytocin levels and changes in cognitive abilities has been found [8]. In addition, estradiol, which is a steroid hormone that is produced during the estrous cycle (the preparatory stage for mating), is known to be maintained at levels proportional to the concentration of hippocampal apical dendritic spines in adult human females. Increased concentrations indicate increased synaptic surface area, which may enhance learning and memory [4, 5]. In a similar animal study, estradiol was injected into ovariectomized female rats, which affected dorsal hippocampal formation (which orchestrates spatial and episodic memories), leading to improvements in memory consolidation [9]. As pregnancy progresses, cortisol levels, which are associated with impairments in hippocampus-dependent cognitive domains such as language and visuospatial memories, rapidly increase. Continued exposure to high levels of cortisol has been shown to impair emotional and cognitive functions like the processing of selective attention and visual components, with associated low scores in most neuropsychological tests compared to normal controls [7, 10]. Similarly, women in their third trimester of pregnancy who have high levels of estradiol and cortisol have significantly lower mean levels of performance on a verbal recall memory task compared to nonpregnant women. However, no significant difference has been found in working memory task performance [6, 11, 12]. Therefore, while hormonal changes during pregnancy and the postpartum period can induce cognitive impairments and neuropsychiatric disorders like postpartum depression, consistent results have not been obtained [13]. Almost no studies have investigated cognitive performance depending on pregnancy and parity status in terms of brain function using ERP. In this study, we used a working memory task to compare parity-dependent levels of cognitive performance. The amplitude of the N100 component, which is the ERP observed during working memory tasks, generally changes depending on the attention being allocated [39]. The P300 component reflects activation of the event-categorization network for attention, judgment, recall, and working memory [21, 22]. In particular, P300 amplitude is directly related to memory, and it reacts sensitively to the activation of attention resources during task execution [40, 41, 42]. Moreover, the P300 amplitude represents the degree of activation of the central nervous system associated with the incoming information processing [43]. The P600 amplitude is sensitive to mild cognitive impairment (memory impairment) and thus provides an objective measurement of memory dysfunction. It has also been reported to be closely related to memory load, memory maintenance, and attention [23, 44, 45, 46, 47].