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Wednesday 26 February 2020

Baby Brain (Things We Don’t Know about Pregnancy Series #14)

Around eight weeks of pregnancy, I started forgetting the names of things.

Some know it as tip-of-tongue syndrome, and it’s definitely not new to pregnancy for me – it’s just worse.

Scissors via Wikipedia Commons.
No wonder I struggled with vocabulary in languages: looking for a pair of scissors, I will do the “scissor gesture” with my fingers and ask “Where are the …?” … “You know, the …?” It sounds odd coming from a writer, but it’s honestly true. I forget words easily. Nouns. These are obviously the least well-coded information at my disposal: after all, I can gesture or describe what I mean – even draw, if I need to, so this was the most easily lost content. Or that’s what I think was happening.

Other women have reported losing track of conversations, being absent-minded, and struggling with tasks such as reading comprehension.

The literature disagrees when it comes to the phenomenon known as “baby brain”. Is it real, or just a figment of women’s imaginations?

Studies focus on different areas of memory . Image via Wikipedia Commons.
No wonder they disagree: most of the studies are very small, and study different areas of memory to each other (as well as attention span and executive function) on women at different stages of pregnancy or early motherhood[1][2][3][4]. Often, measured declines that are statistically significant still fit within the ordinary ranges of working adult memory. Multiple studies, however, have shown that having a baby and being a parent changes your brain, especially in later stages of pregnancy and parenthood, when your brain is the most plastic it ever is in adulthood[5][6][7]. And some suggests it improves memory and brain function[8][9]. This may be because, as some have suggested, baby brain is an important adaptive mechanism, promoting some neurological abilities, such as emotional bonding, at the expense of others.

The most unexplored areas of the baby brain phenomenon are what happens after the immediate postpartum period, and the underlying mechanism behind it. Interestingly, whilst losses in grey matter have been reported in the hippocampus area of mothers’ brains, two years later, brains look the same again as they did before, suggesting that changes may not be permanent[10]!

What are the mechanisms behind baby brain?

Various studies propose different ideas. Some who have suggested that the effects are not “real” think they could be explained by other consequences of pregnancy and early parenthood, including tiredness and disturbed sleep, stress, morning sickness, and mood changes.

Others think hormones are responsible, which rise to 15-40 times their usual levels during pregnancy and effect neurons in the brain! In particular, oxytocin has been explored. This hormones helps contractions during labour, milk production, and bonding between parent and baby. Animal studies have shown links between oxytocin and the nervous system, behaviour, learning and memory. There are few studies in humans[3][11].

Likely conclusions

There are cognitive changes as a result of pregnancy and parenthood, and it’s probable these lead to shifts in attention and cognitive skills and factors that have been flagged up as affected, such as spatial and emotional memories – one way or another. However, they’re probably not bad enough to effect performance at work, and may have bounced back by the time you return to work anyway!

There are many unknowns when it comes to pregnancy, and over the next few months, I’ll be exploring more of them with you. Look out for my next blog post, which will be about caesarians.

Check out our full article on the things we don't know about pregnancy. This article will be updated as we add posts across the coming months.

why don't all references have links?

[1] de Groot, Renate HM, et al. Differences in cognitive performance during pregnancy and early motherhood. Psychological Medicine 36.7 (2006): 1023-1032.
[2] Christensen, Helen, Liana S. Leach, and Andrew Mackinnon. Cognition in pregnancy and motherhood: prospective cohort study. The British Journal of Psychiatry 196.2 (2010): 126-132.
[3] Heinrichs, Markus, et al. Selective amnesic effects of oxytocin on human memory. Physiology & behavior 83.1 (2004): 31-38.
[4] Brett, Matthew, and Sallie Baxendale. Motherhood and memory: a review. Psychoneuroendocrinology 26.4 (2001): 339-362.
[5] Mascaro, Jennifer S., et al. Child gender influences paternal behavior, language, and brain function. Behavioral neuroscience 131.3 (2017): 262.
[6] Barha, Cindy K., and Liisa AM Galea. The maternal 'baby brain' revisited. Nature neuroscience 20.2 (2017): 134.
[7] Kinsley, Craig H., et al. Motherhood and the hormones of pregnancy modify concentrations of hippocampal neuronal dendritic spines. Hormones and behavior 49.2 (2006): 131-142.
[8] Gatewood, Jessica D., et al. Motherhood mitigates aging-related decrements in learning and memory and positively affects brain aging in the rat. Brain research bulletin 66.2 (2005): 91-98.
[9] Tomizawa, Kazuhito, et al. Oxytocin improves long-lasting spatial memory during motherhood through MAP kinase cascade. Nature neuroscience 6.4 (2003): 384.
[10] Davies, Sasha J., et al. Cognitive impairment during pregnancy: a meta‐analysis. Medical Journal of Australia 208.1 (2018): 35-40.!

[11] Tomizawa, Kazuhito, et al. Oxytocin improves long-lasting spatial memory during motherhood through MAP kinase cascade. Nature neuroscience 6.4 (2003): 384.

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