Why It Happens
Pregnancy brain is still a bit of a head-scratcher. A report in the Journal of Clinical and Experimental Neuropsychology reviewed research on the phenomenon and noted that about 80 percent of pregnant women have memory impairment. However, studies failed to yield consistent results. A recent study published in The British Journal of Psychiatry found no significant cognitive differences in pregnant women, women who weren't pregnant, and women post-pregnancy. And the women in these tests didn't know they were under observation for memory problems -- so they didn't become forgetful as the result of a self-fulfilling prophecy.
"Pregnant women read about pregnancy brain in guidebooks, so they have a tendency to downgrade their own competence," notes study author Helen Christensen, Ph.D., director of the Centre for Mental Health Research at The Australian National University, in Canberra. "The idea of pregnancy brain makes them anxious; this might affect studies' results."
However, even if women's brain cells don't change drastically during pregnancy, there's good reason to feel scattered or absentminded. As exciting as pregnancy is, it can be a nerve-racking time -- and research reveals that short-term stress can affect memory. Moreover, you've got so many things to think about at once (doctor visits, stocking your nursery, and creating a birth plan, just to name a few), which is no easy feat for your noggin. "Studies show that the brain is actually incapable of processing two mental tasks at once," says productivity expert Julie Morgenstern, the author of Never Check E-Mail in the Morning. When you toggle back and forth between two tasks, it takes your brain four times longer to process what it's working on. "Something that would normally take just one tightly focused hour may take four," Morgenstern explains.
Hormones might also be working against you. During pregnancy, your levels of progesterone and estrogen -- both of which are linked to memory function -- shoot way up. At these high levels, they may negatively effect the ability to recall information, according to Abbe Macbeth, Ph.D., a former postdoctoral fellow at the National Institute of Mental Health. "However, these hormones also cause the growth of new brain circuits that help mothers focus on the baby when she's born," says Louann Brizendine, M.D., a neuropsychiatrist and the author of The Female Brain. In other words, your brain is laying the groundwork for letting you tune in to your newborn's cries, for example. All of these shifting gears might make some women forgetful -- and unfortunately, the effect may endure even after your baby's arrival, fueled by other hormones that are produced during the breastfeeding process.