Читать книгу Infants and Children in Context - Tara L. Kuther - Страница 145

The developing embryo and fetus receive a great deal of research attention, but what does pregnancy mean for mothers’ development? Women’s bodies undergo a radical transformation during pregnancy. For example, the hormone progesterone increases up to 15-fold and is accompanied by a flood of estrogen that is greater than the lifelong exposure prior to pregnancy. Hormonal shifts are associated with brain changes during puberty as well as later in life. Do the hormonal changes with pregnancy influence women’s brain structure? Animal research suggests that pregnancy is accompanied by neurological changes, including changes in neural receptors, neuron generation, and gene expression, that are long-lasting (Kinsley & Amory-Meyer, 2011). It is likely that pregnancy is also associated with neural changes in humans, but there is little research to date (Hillerer, Jacobs, Fischer, & Aigner, 2014).

In a recent groundbreaking study, Elseine Hoekzema and colleagues (2017) conducted brain scans of women who were attempting to become pregnant for the first time as well as their partners. Women who became pregnant were scanned again after giving birth and at least 2 years later. The fathers and women who had not become pregnant were also assessed. The new mothers experienced reductions in the brain’s gray matter, signifying increased neural efficiency in regions of the brain involved in social cognition, specifically, the ability to sense another person’s emotions and perspective. This corresponds with prior findings suggesting that pregnancy is associated with the enhanced ability to recognize faces, especially those displaying emotions (Pearson, Lightman, & Evans, 2009). Gestational alterations in the brain structures that are implicated in social processes may offer an adaptive advantage to mothers by facilitating their ability to recognize the needs of their children and to promote mother–infant bonding (Hoekzema et al., 2017). The changes in gray matter volume predicted mothers’ attachment to their infants in the postpartum period, as indicated by mothers’ increased neural activity in response to viewing photos of their infant compared with other infants. The pregnancy-related neurological changes were so marked and predictable that all of the women could be classified as having undergone pregnancy or not on the basis of the volume changes in gray matter. Notably, fathers did not show a change in gray matter volume, suggesting that the neural effects of pregnancy are biological in nature rather than associated with the contextual changes that occur with the transition to parenthood.

Pregnancy is not only a period of development for the embryo, but for the mother as well. Brain plasticity during pregnancy and the postpartum period is adaptive, as it helps women adapt to motherhood and the challenges of caring for a newborn. Moreover, research suggests that increased plasticity continues well after birth. One study of brain images of women 1 to 2 days after childbirth and 4–6 weeks later found a rejuvenation effect whereby women’s brains showed enhanced plasticity, appearing on average about 5 years younger in the weeks after birth (Luders et al., 2018). However, some scientists argue that enhanced plasticity can promote development but it may also increase women’s sensitivity to stress and vulnerability to mental disorders, such as depression (Barba-Müller, Craddock, Carmona, & Hoekzema, 2019), underlining the importance of support for new mothers.