Research on the existence of "baby brain" is mixed. The term refers to memory problems, poor concentration and absent-mindedness reported by many women during pregnancy and early motherhood.

A recent review of 20 studies assessing more than 700 pregnant and 500 nonpregnant women concluded that general cognitive functioning, memory and executive functioning were significantly poorer in pregnant women. However, the changes are likely to be noticeable only to the pregnant women and those close to them and less likely to affect job performance.

Other research suggests that memory problems during pregnancy aren't as widespread as believed, but can be seen in women experiencing depression shortly before childbirth.

Beyond the relationship between pregnancy and memory, some researchers are looking at the ways pregnancy might positively change a woman's brain. Another recent study compared the MRI scans of women's brains before pregnancy and after giving birth to the brain scans of women who have never given birth. The scans of women after pregnancy showed changes in brain structure that might help women adapt to motherhood.

If you're pregnant or a new mother, don't assume that you're experiencing a cognitive decline. Becoming a mother involves an emotional and physical transition. If you have any concerns about your moods, talk to your health care provider.