Just How Real Is 'Pregnancy Brain'?

Researchers Find No Evidence That Pregnant Women Have Memory Lapses Known as 'Momnesia'

Reviewed by Louise Chang, MD on February 05, 2010

Feb. 5, 2010 -- Pregnancy and motherhood don't cause women to have memory lapses and other cognitive problems, even though the concept of ''pregnancy brain'' and ''momnesia'' are widely accepted, according to a new Australian study.

''When focused on a task, women who are pregnant or new mothers do not have 'cognitive deficits,' and perform as well as their non-pregnant contemporaries," says the study's lead author Helen Christensen, PhD, a researcher at The Australian National University in Canberra. Her study is published in The British Journal of Psychiatry.

''Women may have memory lapses, and change their focus to children and upcoming birth," she tells WebMD in an email interview. "This does not mean they have lost their capacities."

Many pregnancy guidebooks advise women about the possibility of short-term memory problems during pregnancy, Christensen writes, and some studies done with pregnant women have even supported the idea of ''pregnancy brain.''

But in her research, she found that animal studies were at odds with the human studies. Some researchers even found better learning and memory during pregnancy in their animal studies.

''This suggested to us that the effect of pregnancy or motherhood on cognitive abilities may not have been adequately tested," she writes in the journal. Major flaws in the human research, she states, are a lack of memory testing before the pregnancy occurs in order to get a baseline, a sample size that is too small, and lack of a follow-up period.

Cognitive Tests for Pregnant Women

In her study, Christensen evaluated women who had joined the Personality and Total Health (PATH) Through Life Project, a large community-based study in 1999 that focused on health and well-being. She compared the women and their cognitive test results at four-year intervals, in 2003 and 2007.

Christensen tested 1,241 women (age 20-24) at the start, in 1999, to provide a baseline result. Over the eight years of the study, after subtracting dropouts, 76 women were pregnant at follow-up interviews, either in 2003 or 2007; 188 became moms but were not pregnant at the time of the interview. Another 542 didn't become pregnant. Only first-time moms and women pregnant for the first time were included.

No significant differences were found in those who were pregnant or new moms and those who weren't.

Late pregnancy was associated with poorer performance on a test of mental speed, the researchers found. But overall, no substantial differences were found.

''We will continue to follow the sample, with 542 non-mothers, and an age range of 28 to 32 now,'' she says.

Another Expert's View

The new findings echo those of Ros Crawley, PhD, a research at the University of Sunderland in the U.K.

"In our 2008 study, we compared the performance of pregnant and non-pregnant women on 15 sensitive tests of memory and attention and found very little difference between them," Crawley tells WebMD in an email interview. "We also compared their performance on measures in two driving simulator tasks that more closely mimic a real-world condition task and found no difference."

She's not saying differences are never found between pregnant and non-pregnant women's cognitive skills. "But the differences are not consistent with the degree of self-reported deterioration that pregnant women perceive."

''We have suggested that it may be that pregnant women have internalized a societal stereotype that suggests they will become more forgetful and absentminded," Crawley says.

Deficits that are found, Crawley says, ''are always mild," and she says it may not be the pregnancy, per se. "It could be that similar effects would be found if the effects of other major life events [other than pregnancy] were investigated."

Her bottom line? "It is time that society questions the stereotype of cognitive decline in pregnancy."

Show Sources


Ros Crawley, PhD, reader in cognitive psychology, University of Sunderland, U.K.

Helen Christensen, PhD, professor, The Australia National University, Canberra.

Crawley, R.A. Applied Cognitive Psychology, December 2008; vol 22: pp 1142-1162.

Christensen, H. The British Journal of Psychiatry, February 2010; vol 196: pp 126-132.

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