This is from the link I posted above:
*Published in the February [2010] issue of The British Journal of Psychiatry, the Australian study finds fault with previous studies that support the idea of "pregnancy brain," suggesting they may be flawed because they did not test subjects before they were pregnant, so they do not have a true baseline or starting point. Other studies were found to have sample sizes that were too small to be significant, or the lack of a follow-up period.
The Australian study followed 1,241 women between 1999 and 2007, and concluded there were no substantial differences in cognitive test results between women who were pregnant or were new moms, and those who were not.
"Women may have memory lapses, and change their focus to children and upcoming birth. This does not mean they have lost their capacities," Helen Christensen, Ph.D, the study's lead author and a researcher at the Australian National University of Canberra, tells WebMD.
The Australian findings echo those of a 2008 study done at the University of Sunderland in the U.K. Researcher Ros Crawley, Ph.D, tells WebMD that very little difference was found between the performance of pregnant and nonpregnant women on tests of memory and attention, and on tasks that more closely mimicked real-world situations.
Crawley clarifies that she was not saying differences are never found between the cognitive skills of pregnant and nonpregnant women, but suggests it may be that pregnant women have adopted a social stereotype that suggests they will become more forgetful and absentminded. Crawley concludes that it may be time for society to question the stereotype of "pregnancy brain." *