New research reveals that pregnancy-related brain impairment is present in live-bearing fish, but instead of affecting learning and memory as expected from similar research on mammals, it appears to have a stronger impact on decision-making and sensory reception. There have been many studies into the detrimental impact of pregnancy on mammalian brains, sometimes called “baby brain” or “momnesia” in humans, revealing how the disruption of neurological processes like neurogenesis, or the creation of new neurons, can affect learning and memory. While most fish reproduce by laying eggs, some species are live-bearing, or viviparous, and carry their offspring internally before producing live young. Viviparous species include popular aquarium fish from the family Poeciliidae, such as guppy, molly and platy. Researchers found that while both pregnant and virgin fish were equally successful in cognitive tasks, pregnancy was found to compromise the fish’s ability in decision-making and to interpret scent in the water. But there was no difference in cell proliferation in the regions of the brain most responsible for learning and memory.