Researchers in the US found that contrary to the popular view that having children reduces a woman's brainpower, having children actually improves her lifelong mental agility and protects her brain against the neurodegenerative diseases of old age.
The research was carried out by Dr Craig Kinsley, professor of neuroscience at the University of Richmond, Virginia, and colleagues, and will be presented at the Society for Neuroscience 2008 conference which is to take place from 15 to 19 November in Washington DC.
Kinsley said that while a woman may experience an apparent loss of brain function while she is pregnant, this could be because parts of her brain are being remodelled in preparation for dealing with the complicated demands of childrearing.
"The changes that kick in then could last for the rest of their lives, bolstering cognitive abilities and protecting them against degenerative diseases," said Kinsley, according to a Times Online report.
A number of studies have reported that women appear to reduce their memory and reasoning ability when they are pregnant. But Kinsley and colleagues suggest this is a temporary result of the remodelling that is going on, which in the long term boosts the woman's brainpower beyond what she had before she was expecting.
The researchers studied rats and primates and compared the brains and skills of females with and without offspring. As well as physical brain differences, they found that females with offspring were braver, could find food up to five times more quickly, and had better spatial ability than females without offspring.
Among the physical differences in the brains of mothers versus non-mothers, the researchers found that nerve cells in parts of the brain important for tending to offspring were larger and more richly connected to other cells. The mothers' brains also showed newly formed clusters of cells that the researchers referred to as "maternal circuits".
Although most studies like this are done on animals, said Kinsley, it's likely that human women will also have similar benefits because the same regions of the brain are used in maternal behaviours.
Another study by Australian researchers took issue with the idea that women's mental powers diminish during pregnancy.
Mental health scientists at the Australian National University recently found there was no evidence that cognitive function declines during pregnancy. They interviewed 2,500 women aged from 20 to 24, first in 1999 and then in 2003 and 2007.
They found that the women who were pregnant during the second or third batch of interviews performed the same on tests of logic and memory as they did before, and there was no difference between the pregnant women and the controls.
Lead researcher Professor Helen Christensen told AFP:
"It really leaves the question open as to why [pregnant] women think they have poor memories when the best evidence we have is that they don't."
Perhaps women notice minor lapses in mental ability and then attribute it to being pregnant because that is the most significant thing in their mind at the time.
Christensen said perhaps it was easier to "attribute what might be just normal lapses in memory to pregnancy". She told reporters that mother rats were much better at multi-tasking than non-mothers, they were better at finding their way through mazes and they were less anxious and fearful.