Adjusted percentage difference in plasma PCB concentrations by reproductive and parity/lactation (percentage difference comparing parous women who breastfed ≥6 months with nulliparous women) and b) participant herself breastfed as an infant (percentage difference comparing those breastfed for ≥3 months with those who were not breastfed). Results are adjusted for age, marital status, education, income, smoking history, alcohol use, BMI, parity, lactation, birth order, breastfed as an infant, intakes of fish, meat, poultry, eggs, and dairy, and occupation. DL-PCBs=dioxin-like PCBs; HOND-PCBs=hepta, octa=, nona-, deca-substituted PCBs; PCB-4=PCBs 105, 118, 138/158, 180; PCB>50=PCBs with >50% detection in cohort; PH-PCBs=penta, hexa-substituted PCBs; TT-PCBs=tri, tetra-substituted PCBs; WG1B=Wolff group 1B PCBs; WG2A=Wolff group 2A PCBs; WG2B=Wolff group 2B PCBs; WG3=Wolff group 3 PCBs