# Effect of Childbirth Experience on Cognitive Performance and Event-Related Potential Patterns
## 1 Introduction  
In self-report evaluations regarding the occurrence of depression after childbirth and the negative effects of pregnancy, difficulty concentrating and short-term memory loss, among other symptoms, were reported [1, 2]. Anxiety about the decline in cognitive function associated with pregnancy is thought to be due to an increase in psychological and physical stress [3]. However, scientific evidence of this phenomenon has not been clearly established. Most previous studies have suggested that these symptoms can be explained by hormonal and cognitive changes that occur during pregnancy and in the post-partum period. In other words, hormones like oxytocin, estradiol, and cortisol, which vary greatly during pregnancy and childbirth, are known to induce cognitive changes [3, 4, 5, 6, 7, 8, 9, 10, 11, 12]. Although there have been various attempts to objectively observe the changes in cognitive performance in pregnant women and mothers, results have not been consistent [1, 13]. It has been reported that a decline in memory occurs due to the effects of pregnancy and that a decrease in gray matter volume in the hippocampal region related to memory is recovered only two to three years after childbirth [9, 14]. However, no significant changes in memory have been found after pregnancy, and no consistent results have been reported [1, 8, 9, 14, 15, 16]. There have also been reports of deficits in attention, changes in language expression skills, cognitive decline, and memory loss during pregnancy. It has beensuggested that these are not objective changes caused by hormones but rather are related to sudden changes in sleep patterns (sleep time, sleep quality, insomnia, etc.) [17,18] due to factors such as fetal movement and urinary frequency during pregnancy [19,20]. Moreover, the decline in cognitive function during pregnancy has been attributed to the increase in psychological and physical stress [3]. To date, changes in cognitive performance, hormones, brain volume, and the surrounding environment, as well as stress, have been correlated with cognitive changes during pregnancy and/or childbirth; however, it has been difficult to produce consistent results. Therefore, to more accurately verify the correlation between pregnancy/birth and cognitive changes, further research based on biosignals, which can serve as another objective evaluation index, is required. In particular, the amplitude of the event-related potential (ERP) parameters of electroencephalogram (EEG) signals during a cognitive task can be used to clearly indicate task performance [21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35]. During the performance of working memory tasks, EEG activity appears in the midfrontal and occipital cortex regions [21,22,24, 25, 26, 27, 28]. Among the extractable ERP components, the amplitude of the P300 element is processed when determining whether a presented stimulus is consistent or inconsistent with a previous stimulus during trials [22] and is known to reflect the process of updating memory [29] and the allocation of surrounding resources [30,31]. In the case of language tasks, activation has been reported in the posterior region of the brain with the N400 component, which reflects semantic processing [32], and the P600 components, which reflect re-analysis processes that correct the initial syntactic analysis [23,33]. For spatial tasks, ERP has been clearly observed in the Pz domain, with alterations in the amplitudes of the components P200 and P300 [34]. In other words, the ERP appears to be associated with different components according to the type of task, which suggests that the components represent different brain activity patterns [35]. In addition, changes in amplitude among ERP components are related to cognitive behavior, so it is an objective indicator suitable for comparing more precise cognitive performance. To better understand the effect of pregnancy on cognitive function, this study aimed to objectively show whether a decrease in cognitive performance occurs in women after childbirth.