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Abstract

We agree that the behavioral and biologic changes involved in reproduction are widespread and bidirectional. Friedman’s reference to Kinsley et al’s1Kinsley C Madonia L Gifford GW Tureski K Griffin GR Lowry C et al.Motherhood improves learning and memory.Nature. 1999; 402: 137-138Crossref PubMed Scopus (238) Google Scholar recent paper demonstrating that motherhood increases learning and memory does illustrate the bidirectional nature of these changes nicely. The Kinsley paper also raises another issue that should be considered when conducting research on the biologic and psychologic changes associated with pregnancy and motherhood. This paper is one suggesting that neurologic changes in the peripartum period are largely preparatory—priming the mother for the challenges of parenting. However, it may be that these peripartum changes are simply a result of the dramatic physiologic changes necessary to maintain and effect successful pregnancy and parturition. Viewing the function of changes in the peripartum period as the beginning of the postpartum process should be treated with caution for at least 2 reasons. First, the biology of pregnancy is quite different from the biology of the postpartum period (though we do recognize that some changes initiated in the peripartum period appear to extend into the postpartum period2da Costa APC Wood S Ingram CD Lightman SL Region- specific reduction in stress-induced c-fos mRNA expression during pregnancy and lactation.Brain Res. 1996; 742: 177-184Crossref PubMed Scopus (126) Google Scholar). Second, the behavioral, cognitive, and affective changes associated with these periods appear to be quite different. This is brought into clear relief by a comparison of the animal study cited by Friedman with pregnancy-associated memory changes in human beings.3Brett M Baxendale S Motherhood and memory: a review.Psychoneuroendocrinology. 2001; 26: 339-362Abstract Full Text Full Text PDF PubMed Scopus (142) Google Scholar Kinsley et al show that learning and memory in rats are enhanced as a function of parenting. In contrast, the available evidence on memory in pregnancy in human beings suggests that it is diminished, with the few studies on postpartum memory showing no enhancement (but also no decrement). Similarly, we have shown in our paper that emotional responses to stress in women are dampened during pregnancy, while postpartum emotional responses are similar to prepregnancy responses. These examples suggest that the cognitive and affective changes occurring before parturition that are functional during this period may or may not be so during the postpartum period. Future research, examining the biologic, affective, and cognitive changes associated with reproduction will be better served if these 2 periods are considered as potentially different and separate until the evidence suggests otherwise.