Chapman University Chapman University Digital Commons Psychology Faculty Articles and Research Psychology 2012 Increasing Parity is Associated with Cumulative Effects on Memory Laura M. Glynn Chapman University, [email protected] Follow this and additional works at: http://digitalcommons.chapman.edu/psychology_articles Part of the Cognition and Perception Commons, Family, Life Course, and Society Commons, Gender and Sexuality Commons, Health Psychology Commons, Maternal and Child Health Commons, Mental and Social Health Commons, Neurosciences Commons, Obstetrics and Gynecology Commons, and the Women's Health Commons Recommended Citation Glynn, LM (2012). Increasing parity is associated with cumulative effects on memory. Journal of Women’s Health, 21, 1038-1048. DOI:10.1089/jwh.2011.3206 This Article is brought to you for free and open access by the Psychology at Chapman University Digital Commons. It has been accepted for inclusion in Psychology Faculty Articles and Research by an authorized administrator of Chapman University Digital Commons. For more information, please contact [email protected]. Increasing Parity is Associated with Cumulative Effects on Memory Comments This is a copy of an article published in the Journal of Women's Health © 2012 Mary Ann Liebert, Inc., available online at DOI:10.1089/jwh.2011.3206 Copyright Mary Ann Liebert This article is available at Chapman University Digital Commons: http://digitalcommons.chapman.edu/psychology_articles/20 JOURNAL OF WOMEN’S HEALTH Volume 21, Number 10, 2012 ª Mary Ann Liebert, Inc. DOI: 10.1089/jwh.2011.3206 Increasing Parity Is Associated with Cumulative Effects on Memory Laura M. Glynn, Ph.D. Abstract Background: The purpose of this investigation was to determine if reproductive experience is associated with cumulative effects on human memory performance during pregnancy and if these effects persist into the postpartum period. Methods: Verbal recall memory performance was assessed in 254 women four times during pregnancy and at 3 months postpartum. The relation between parity and memory function was evaluated with hierarchical linear modeling and analysis of covariance (ANCOVA). Results: The data indicate that the previously documented adverse effects of pregnancy on memory perfor- mance are compounded with successive pregnancies. During gestation and postpartum, multiparity was as- sociated with poorer memory function, and these effects did not appear to be due to differences in maternal demographics, depressive symptoms, or sleep quality. Conclusions: Animal models demonstrate that the effects of reproduction on brain structure and function are both cumulative and enduring. However, little is known about the influence of reproductive experience on the human female brain. These findings provide evidence that in humans, reproduction is associated with striking and perhaps persisting changes in cognitive function. Introduction Specifically, females who have given birth display improved memory function that is present into old age, and they also n the life span of the human female, no other naturally appear to be protected from aging-associated neurodegen- Ioccurring hormone exposures are more extreme than those eration.10–12 Second, some studies have shown that the effects experienced during pregnancy, birth, and lactation. For ex- of pregnancy are cumulative; that is, with successive litters ample, during gestation, estradiol levels increase to 30 times and more mothering experience, the effects on function are greater than the peak during the menstrual cycle, and cortisol greater. Multiparous females display enhanced cognitive reaches levels similar to those in Cushing’s syndrome and function compared to primiparous and nulliparous fe- major melancholic depression.1–3 A substantial literature ex- males,10,12 although not all studies demonstrate this effect.13 ists indicating that less extreme endocrine events, such as Taken together, these findings suggest that parity imparts a puberty and menopause, which mark the onset and conclu- lasting imprint on the brain and behavior of the female rodent. sion of the period in which the female is capable of repro- In light of these pervasive and long-term changes observed in duction, are associated with changes in both brain structure nonhuman animals and the dramatic hormone exposures that and function.4,5 In contrast, almost nothing is known about characterize the prenatal endocrine milieu, it seems likely that how the hormone exposures linked to reproductive experi- pregnancy also exerts persisting influences on the human ence influence the brain and behavior of the human female. brain. In spite of this, a critical gap in our understanding of Work with rodent models has repeatedly demonstrated that women’s mental health exists. The nature of changes in brain alterations in cognitive performance and underlying neural and behavior that are affected by pregnancy and whether or systems emerge during pregnancy.6–9 Further, these changes not these alterations persist beyond parturition have yet to be appear to be enduring in nature, a fact that is supported by determined. two lines of evidence. First, parous rodents show alterations In humans, a number of studies have shown that memory in cognitive function that persist throughout the life span. function declines during pregnancy, with the majority Crean School of Health and Life Sciences, Chapman University, Orange, California, and Department of Psychiatry & Human Behavior, University of California Irvine, Irvine, California. 1038 PARITY AND MEMORY 1039 Table 1. Participant Characteristics Characteristic Primiparous (n = 113) Multiparous (n = 141) t or Chi-square p value Race/ethnicity (%) Latina 27 45 11.5 0.01 Non-Hispanic white 50 40 Asian 13 6 Other 10 9 Maternal age (years) 27.9 30.3 - 3.5 0.00 Education (%) 15.2 0.00 High school or less 17 17 Associates or vocational degree 32 51 4-year college degree 29 24 Graduate degree 22 8 Prenatal depression (CESD) 1.42 1.67 - 1.1 0.26 Postpartum depression (EPDS) 5.0 5.6 - 0.9 0.34 Prenatal sleep quality 5.4 5.6 - 0.4 0.68 Postpartum sleep quality 6.2 7.2 - 1.5 0.14 CESD, Center for Epidemiological Studies Depression Scale; EPDS, Edinburgh Postnatal Depression Scale. detecting adverse influences on verbal recall memory (for a dysregulate neuroendocrine function. Participant character- review and meta-analysis, see reference 14). In humans, the istics are shown in Table 1. persistence of these effects is not well understood, however, because few studies have examined postpartum memory Overview of study design performance.15–18 Two studies have compared function dur- Pregnant participants were recruited by a research nurse ing gestation and postpartum to performance of women who during the first trimester of pregnancy. The women then were not pregnant. These suggest that diminished memory participated in study visits at 14–16 (mean [M] 15.31, standard performance persists as late as 32 weeks postpartum.17,18 deviation [SD] 0.92), 24–26 (M 25.55, SD 0.93), 30–32 (M 30.96, Even less is known about the cumulative effects of repeated SD 0.77), and 36 + weeks’ gestation (M 36.7, SD 0.83) and also pregnancy experience in women. To date, no large study has at 12–14 weeks postpartum (M 13.24, SD 1.08). At each visit, examined the effects of parity on memory performance dur- memory performance was assessed. The study was approved ing pregnancy or the postpartum period. The one investiga- by the University of California Irvine Institutional Review tion of parity compared the performance of 22 primiparous Board, and all participants provided informed consent. and 26 multiparous women to the performance of nonpreg- nant women at a single point in gestation. The findings sug- Dating of pregnancy and determination gested that parity exerts additive effects on cognitive of pregnancy history performance because the decrement in verbal recall memory performance was largest for the multiparous women.19 Prior pregnancy history was determined through medical The purpose of the present longitudinal study is to further interview and prenatal chart review conducted by a research examine, in a large sample of women, if multiple pregnancies nurse. Current pregnancies were dated according to current (increased parity) are associated with cumulative effects on American College of Obstetricians and Gynecologists memory function during pregnancy. Moreover, the enduring (ACOG) guidelines20 by comparison of last menstrual period influence of reproductive experience will be assessed during to estimates based on early ultrasound measurements by the the postpartum period. The study focused on verbal recall research nurse at the first study visit at 15 weeks’ gestation. memory because the small body of existing literature suggests that this component of memory is most sensitive to the hor- Memory assessment mone exposures of pregnancy and also may differ depending Verbal recall memory was assessed with a paired-associ- on parity.14,18 It was predicted that pregnant women who had ates learning task. For this task, three sets of 12 unrelated given birth previously would exhibit the largest decrements word pairs were presented verbally. Immediately after pre- in memory performance. It was further predicted that these sentation of each set of pairs, the participant was given the cumulative effects of parity would persist at 3 months post- first word of each pair and was asked to supply the second partum. word. The word pair lists were constructed from randomly chosen words