Pregnancy requires a lot of preparation, including countless physiological and behavioral adjustments throughout pregnancy to provide an appropriate environment for embryonic development. It is very common that pregnant women crave tasty foods at certain stages of pregnancy, which often leads to weight gain and even obesity. 
April 4, local time, international academic journal Nature Metabolism has published online a study by researchers from a team including the Auguste Pierre Sunil Institute for Biomedical Research (IDIBAPS) in Spain, which found in mice , food cravings during pregnancy are driven by dopamine signaling in the brain’s reward system.
Although the craving for tasty food is a common feature of pregnancy and may lead to weight gain or even obesity, the neurobiological mechanism remains unclear, including Part of the reason is the difficulty of simulating this behavior in the lab. 
During pregnancy, perception of sweetness and food craving behaviors increase.
In addition to this study, they designed an experiment that could measure food craving-like behaviors in pregnant mice. Research has revealed that pregnancy affects brain connectivity, particularly components of the dopamine circuit that is involved in the perception of rewarding stimuli and drives behaviors such as food cravings. 
Brain functional networks related to reward and mood increase briefly during pregnancy.
Importantly, these preliminary findings also show that persistent food craving behaviors by mothers can have long-term metabolic effects in offspring, especially male offspring. Pups of pregnant mice allowed to engage in food craving-like behaviors develop glucose intolerance, weight gain, and are more prone to eating disorders and anxiety in adulthood compared to controlsbehavior.
The research team believes that the above results bring new insights into the neuronal basis of pregnancy-related food cravings, reveal the nature of food cravings after pregnancy, and advocate for Moderate emotional eating during pregnancy to prevent neuropsychological and metabolic health problems in offspring.
Nature-Metabolism also published a “News and Views” article, in which Serge Luquet and Giuseppe Gangarossa from CNRS stressed that “the need for Further research is needed to determine which hormonal, nutritional and environmental factors create windows of vulnerability during pregnancy, and to investigate whether human genetic diversity influences the brain’s resilience or susceptibility to food craving attacks during pregnancy.”
Paper link: https://www.nature.com/articles/s42255-022-00557-1