Prolactin is a protein hormone that plays a regulating role in many physiological processes across mammalian species, but the two primary functions it exerts are the development of the mammary glands and milk production. This review will focus on the potential key role of prolactin in the hormonal control of maternal investment and survival in mammals. Prolactin has been demonstrated to influence maternal investment throughout the complete investment process from ovulation and implantation to gestation and lactation, highlighting its essential role in this balance. Different stressors may affect prolactin secretion, and therefore, be a trigger to lower or stop maternal investment. Hence, comprehending prolactin's function in maternal investment and survival strategies can have important implications for our understanding of reproductive success and failure, potentially benefiting conservation efforts to protect endangered species. Since the role of prolactin is inconsistent in different mammalian species, species-specific research is mandatory to determine the exact role of prolactin in individual maternal survival-investment strategies. The current knowledge on this topic is highlighted in the present review but is also illustrative of the fact that many areas of prolactin related research remain underexposed.
