A new study with lab rats suggests hormonal changes in pregnancy and childbirth could affect brain function in women as they age. (Source: ScienceDaily.com)

Researchers at the University of British Columbia studied the impact of two types of estrogen hormones on the rats’ brains.

Estradiol gave female rats an edge in cognitive behavior compared to all the females on estrone, which is a predominant form of estrogen in older women, whether the test subjects had given birth or not.

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Estrone, meanwhile, impaired learning ability in middle-aged rats who had given birth but improved learning ability in rats that had never had babies.

"Our most recent research shows that previous motherhood alters cognition and neuroplasticity in response to hormone therapy, demonstrating that motherhood permanently alters the brain," according to researcher Dr. Liisa Galea.

Why does it matter? Researchers say it could affect the way women use hormone replacement therapy, taking into account whether or not they have had children.