It speaks for itself that pregnancy elicits all kinds of change in a woman’s body. From the blatantly obvious (weight gain and so on) to less overt changes (changes in appetite and the like). The hormone balances in the female body also change during and shortly after pregnancy. This has a myriad of effects, such as mood change and the development of an unconditional feeling of love for the newly born son or daughter.

Recently, a new change in pregnant women has been found. It turns out that mothers have bigger brains.

Scanning Mother Brains

Aided with high resolution magnetic resonance images (MRIs), researchers have observed the brains of 19 women who had just given birth (10 of them gave birth to a son, the others to a daughter). The women in this study were 33 years old on average and none of them was subjected to postnatal depression.

Brain scans were made two to three weeks after giving birth, and once again three to four months later.

Subsequently, these images were compared with each other.

Grey Matter

These images showed that the grey matter in certain brain areas had slightly (but significantly) increased. Normally, the grey matter in an adult human brain does not increase in a period of just a few months, except in extensive learning processes, brain damage or illness.

The brain regions of which the grey matter increased were those involved in rewarding and emotional processes, as well as the development of a ‘mother feeling’. Those mothers that were most enthusiast about their child exhibited the highest increase in size of certain midbrain areas.

Further Research

The researchers emphasize that their findings should be confirmed and their observations repeated. For example, an experiment with adoptive mothers might elucidate the interaction between postnatal hormones and the mother-child relationship. This, in turn, might lead to more clarity concerning the question whether it is the brains that influence the behavior, the behavior that influences the brain, or, perhaps most likely, both.

A greater understanding in these matters might help explaining why some women suffer from postnatal depression and others do not.

References

American Psychological Association (20 October 2010). The Real ‘Mommy Brain’: New Mothers Grew Bigger Brains Within Months of Giving Birth.
Kim, P.; Leckman, J.F.; Mayes, L.C.; Feldman, R.; Wang, X. & Swain, J.E. (2010). The plasticity of the human maternal brain: Longitudinal changes in brain anatomy during the early postpartum period. Behavioral Neuroscience. 124(5), pp. 695 – 700.
Kinsley, C.H. & Meyer, E.A. (2010). The construction of the maternal brain: Theoretical comment on Kim et al. (2010). Behavioral Neuroscience. 124(5), pp. 710 – 714.