Motherhood and the Brain
Imagine: It is 3 am, the baby is crying, mom jumps to her feet and runs to feed or soothe the need of this precious infant. This is an instinct for many mothers, this desire to nurture, care for, and foster the mother-child relationship. From a neurological perspective, there’s a lot that goes on in that instinct! A mother’s brain undergoes natural chemical, physical, and biological changes in pregnancy, birth, and beyond.
Gray Matter and “Mom Brain”
Many women joke about “mom brain.” Mothers regularly feel like they become more forgetful during pregnancy and after having their child. There is a reason for this, and it has to do with the structure of your brain.
In the brain, there is something called “gray matter.” Gray matter is in charge of muscle control, processing memories, emotions, and decision-making (Gritters, 2020). During pregnancy and after giving birth, gray matter in a mother’s brain actually reduces in certain areas. This is called “synaptic pruning” (Hoekzema et al., 2017). Synapses or connections in the brain are being reorganized to account for new responsibilities and concerns.
These changes last for around two years after birth (Oatridge et al., 2002). Think about it—it is usually around this time that mothers are constantly aware and checking on toddlers to make sure they are cared for. This is also when children are learning to self-regulate and be a bit more autonomous (with their parents nearby). Gray matter stays this way for about two years because babies and toddlers are so dependent in this stage of their lives.
Other areas of a mother's brain are fostering new connections by bonding with her baby. One study found that the hippocampus (the part of the brain responsible for memory and learning) showed decreases in gray matter, but this same area lit up when a mother looked at her baby (Orchard et al., 2023). Research was even able to differentiate groups of women who were not mothers just based on whether or not these changes took place in the brain (Hoekzema et al., 2017)!
Nursing, Weaning, and Motherhood
When a mother nurses, there is a beautiful exchange happening. Oxytocin and an influx of hormones facilitate this bond in nursing and also are what create breast milk (World Health Organization, 2009). With these chemical exchanges happening constantly, the body is in a constant state of response to the child and their needs. In the postpartum period, a shift occurs in which the mother has to put her needs to the side to care for the needs of the baby.
One study noted that weaning, which frequently happens a year or more after birth, may even be a factor in the return of “typical” neural and cognitive development (Orchard et al., 2023). This cognitive load is important to note because the weaning transition can be a vulnerable time for mothers (Orchard et al., 2023). This brain function does resolve in the postpartum period (Orchard et al., 2023).
Synaptic pruning or less gray matter might sound bad or unhelpful, but in actuality, it is the best thing for the baby. These changes in the brain promote bonding and adequate care for the baby. Studies even find that brain plasticity (the brain’s ability to change) is particularly high during pregnancy and postpartum—allowing it to reorganize itself well (Orchard et al., 2023). In this postpartum stage, the brain's systems reorganize to care for an infant and the necessities of the mother. Moreover, this all lines up with attachment theory; bonding is the foundation for healthy attachment to the caregiver, which leads to healthy attachments and relationships later in life.
The Special Journey of Motherhood
Motherhood is a special journey that involves many chemical, physical, and physiological changes to allow a precious new life into the world. As seen, the research points to the beauty of the incredible changes that accommodate new life in the brain and in the world around them. Growing bodies of research express what new mothers experience to be true: parenthood is a large and often difficult transition. If you’re on this special journey and feeling the many changes and challenges of new motherhood, you’re not alone.
References
Gritters, Jenni. “This Is Your Brain on Motherhood.” The New York Times, 5 May 2020,
www.nytimes.com/2020/05/05/parenting/mommy-brain-science.html
Hoekzema, E., Barba-Müller, E., Pozzobon, C. et al. “Pregnancy leads to long-lasting changes in human brain structure.” Nat Neurosci 20, 287–296 (2017). https://doi.org/10.1038/nn.4458
Oatridge, A., Holdcroft, A., Saeed, N., Hajnal, J.V., Puri, B.K., Fusi, L., Bydder, G.M. “Change in Brain Size during and after Pregnancy: Study in Healthy Women and Women with Preeclampsia.” American Journal of Neuroradiology, vol. 23, no. 1, 1 Jan. 2002, pp. 19–26, www.ajnr.org/content/23/1/19.
Orchard, Edwina R., et al. “Matrescence: Lifetime Impact of Motherhood on Cognition and the Brain.” Trends in Cognitive Sciences, vol. 27, no. 3, Jan. 2023, https://doi.org/10.1016/j.tics.2022.12.002.
World Health Organization. “The Physiological Basis of Breastfeeding.” Nih.gov, World Health Organization, 2009, www.ncbi.nlm.nih.gov/books/NBK148970/.