New Study Reveals How Pregnancy Changes the Brain to Trigger Food Cravings

Pregnancy may change brain reward circuits in ways that make highly palatable foods more difficult to resist, according to a study in mice. Researchers identified a serotonin-related brain mechanism that may help explain the biological basis of pregnancy-associated food cravings.

Published in Nature Neuroscience, the study examined serotonin-producing neurons in the dorsal raphe nucleus, a brain region involved in regulating motivation and behaviour. During pregnancy, these neurons became less active, while the animals showed increased food-craving-like behaviour.

Researchers found that activity of the SK3 potassium channel increased in these serotonin neurons during pregnancy. SK3 helps control whether neurons fire, and higher activity reduced serotonin-neuron firing. When researchers removed SK3 specifically from these neurons, the pregnancy-associated reduction in neuronal activity was prevented and craving-like behaviour was substantially reduced.

Conversely, increasing SK3 activity in nonpregnant female mice produced changes in neuronal activity and food-seeking behaviour resembling those observed during pregnancy.

The team also identified a pathway linking serotonin neurons in the dorsal raphe nucleus with the ventral tegmental area, a brain region involved in reward and motivation. Activating this pathway reduced craving-like behaviour in pregnant animals, while inhibiting it increased the behaviour in nonpregnant animals.

Together, the findings suggest that pregnancy may increase SK3 activity, suppress serotonin signalling and alter communication within reward-related brain circuits. These changes could contribute to stronger motivation for highly palatable foods.

However, the findings are based entirely on animal models and do not establish that the same mechanism occurs in pregnant women. Directly altering serotonin signalling during pregnancy could also carry risks.

Further human studies are needed to determine whether hormonal and other physiological changes during pregnancy influence SK3 activity and serotonin pathways, and whether the mechanism could eventually help understand excessive weight gain or maternal obesity.

REFERENCE: Zhao, Q., et al. (2026). Serotonin neurons in the dorsal raphe control food-craving-like behavior during pregnancy in mice. Nature Neuroscience. DOI: 10.1038/s41593-026-02445-3. https://www.nature.com/articles/s41593-026-02445-3