Maternal Cadmium Exposure Impairs Lactational Performance and Milk Quality in Mice

Cadmium (Cd) is a ubiquitous heavy metal environmental toxicant, and exposure poses a persistent public health concern due to its bioaccumulative properties. However, the impact of maternal Cd exposure on mammary gland function during lactation remains insufficiently understood. In this study, we investigated the effects of Cd exposure during pregnancy and lactation on mammary gland development, hormonal homeostasis, and lactational performance using a drinking water exposure model. Pregnant 7-week-old ICR mice were randomly assigned into Control and Cd groups. The Control group received standard drinking water, while the Cd group was administered water supplemented with Cd (12 mg/L). Results demonstrated that maternal Cd exposure markedly reduced maternal and offspring weight, respectively. Histological analysis revealed that Cd exposure resulted in decreased numbers of mammary alveoli and widened interstitial spaces, indicating impaired mammary development. In addition, Cd exposure markedly compromised lactational performance, as reflected by reduced milk yield and decreased levels of milk protein, fat, and lactose across multiple lactation stages. Integrated metabolomic and transcriptomic analyses further revealed substantial alterations in hormonal profiles and metabolic pathways associated with mammary gland function. Notably, Cd accumulation was detected in mammary tissue and milk, accompanied by transcriptional changes in genes involved in milk synthesis and lipid metabolism. In conclusion, these findings indicated that maternal Cd exposure during pregnancy and lactation is associated with structural and functional alterations of the mammary gland, leading to reduced lactational performance and impaired offspring growth. The findings contribute to a better understanding of the risks posed by environmental Cd exposure, emphasizing the need for effective public health strategies to mitigate its impact on maternal and infant health.