a colloquial term for the memory deficits, reasoning, and spatial learning difficulties, and other cognitive problems popularly believed to be experienced by pregnant women. Although often attributed to increases in hormone levels and external stressors, the baby brain remains controversial among medical professionals, many of whom dispute not just its supposed characteristic but its very existence. Critics contend that the phenomenon actually results from sleep deprivation and inaccurate self-reports of problems. Additionally, empirical research is limited and contradictory. Although some studies provide support for the phenomenon, showing temporarily diminished brain volume in women during pregnancy and a smaller hippocampus in pregnant than in nonpregnant rats, others indicate that pregnancy does not adversely affect cognition and may actually enhance it. Also called pregnancy brain.