Chlorinated pesticides (CP) are environmentally persistent pollutants that (prenatally through the placenta and post-natally via breastfeeding) are transferred from mother to child. Considering the significant bleeding tendency noted in infants of CP-intoxicated mothers in Egypt, this study aimed to investigate any correlation between levels of these xenobiotics in mothers' milk and bleeding tendencies of their infants, as well as a possible role of any related immunosuppression in this phenomenon. This study examined 180 newborns presenting with altered bleeding tendencies and their mothers, and 180 normal newborns and their mothers (serving as a controls), selected from the Breastfeeding Unit, Center for Social and Preventive Medicine at the Cairo University Pediatric Hospital. Chlorinated pesticides (e.g., hexachlorocyclohexane, DDT, hepta-chloroepoxide, α- and β-endosulfan, aldrin, endrin, dieldrin) levels and their derivatives were measured in mothers' milk as well as in serum of neonates using gas chromatography/high resolution mass spectrometry. To link bleeding tendency with lactational intoxication of neonates by CP, newborns' blood was assessed for: platelet count, bleeding and prothrombin time, liver enzymes, Vitamin K, TNFα, and IL-10. Breast milk CP levels were associated with a higher incidence of bleeding in infants. Interference with the coagulation cascade was supported by changes in prothrombin time (prolonged), platelet counts (decreased), liver enzymes (increased), and serum vitamin K concentrations (decreased). Moreover, the significant decrease in WBC count and lymphocytes added to depressed cytokine secretion, i.e., TNFα and IL-10, suggested an organochlorine-induced immunotoxicity in infants developmentally exposed to the agents. We conclude that maternal transfer of CP, via breastfeeding or across the placenta, was sufficient to achieve similar CP levels in the serum of their infants; this correlated with a manifesting of altered bleeding tendencies and perturbed cytokine biology in these infants.