Researchers at the University of Montreal say newborns whose mothers did at least this much moderate cardiovascular exercise during the last two trimesters of pregnancy seemed to have a cognitive head start, based on EEG testing, compared to infants whose mothers were sedentary.
"Our results show that the babies born from the mothers who were physically active have a more mature cerebral activation, suggesting that their brains developed more rapidly," said lead author Elise Labonte-LeMoyne, a PhD candidate in exercise science.
To determine the impact of maternal exercise on fetal brain development, researchers performed EEG, or electroencephalography, on 18 infants about 10 days after their births. Ten of the newborns' mothers were randomly assigned to exercise during pregnancy, while the other eight babies' mothers were not.
EEG measures electrical activity in the brain.
Labonte-LeMoyne said each newborn was allowed to fall asleep in their mother's lap. The infant's head was then fitted with a bathing cap-like netting dotted with 124 electrodes, which were cushioned with a spongy material to prevent irritation.
The electrodes pick up electrical impulses in the brain in response to stimuli, in this case a test called auditory memory or sound discrimination.
"We play them sounds — a beep, beep, beep kind of thing — then there's a different sound that's a slightly higher pitch, and we're looking at the brain's ability to see that as a different sound and react to the fact that it's a different sound," Labonte-LeMoyne said from Montreal.
"This is of interest because the ability to discriminate sound is very important in language development and it is something that is present at birth, whereas most other cognitive functions aren't quite there yet."
She said that in this test, a smaller wave on an EEG reading is better, and that's what was observed in the newborns whose mothers exercised.
"Their wave was about half the size of the (sedentary) group. Basically, they need less energy to do the same test, they're refining their process ... it's a more mature response."
All 10 of the infants whose mothers exercised had the reaction to the sound stimuli and their average wave reading was significantly smaller than that of babies in the non-exercise group.
"What we really conclude is that they matured sooner, and by exercising, which appears to have no downside, you give an advantage to your child," said Labonte-LeMoyne, who presented the team's findings Sunday at the Neuroscience 2013 congress in San Diego.
The researchers aren't sure why maternal exercise may boost newborn cognition, but one hypothesis is that increased oxygen uptake benefits the developing fetus as well as the mother.
In the past, obstetricians typically advised women to take it easy and rest during pregnancy, but it's now more commonly accepted that inactivity can be detrimental.
"While being sedentary increases the risks of suffering complications during pregnancy, being active can ease post-partum recovery, make pregnancy more comfortable and reduce the risk of obesity in the children," said co-researcher Daniel Curnier, a professor of kinesiology at the university.
"Given that exercise has been demonstrated to be beneficial for the adult's brain, we hypothesized that it could also be beneficial for the unborn child through the mother's actions," he said.
Such a head start could affect a child's entire life, said principal investigator Dave Ellemberg, also a professor in the department of kinesiology.
"We hope these results will guide public health interventions and research on brain plasticity," he said. "Most of all, we are optimistic that this will encourage women to change their health habits, given that the simple act of exercising during pregnancy could make a difference for their child's future."
Ideally, the next step would be to evaluate the children's cognitive, motor and language development when they reach 12 months of age to determine if cognitive differences are maintained, Labonte-LeMoyne said.