Fig. 2: The dose-risk association of lactation duration with ischemic heart disease in parous postmenopausal females (N = 130,147).

Notes: IHD ischemic heart disease, aHR adjusted hazard ratio, CI confidence interval. a–c represent the dose–risk association of IHD with lifetime, per-child, and first-child lactation durations, respectively. Colors in yellow, blue, and purple represent lactation duration of a lifetime, per child, and first child, respectively. The shading indicates the 95% CI of the aHR for IHD. Model was adjusted for age, marital status, residence, highest education attainment, occupation, annual household income, body mass index, waist circumference, smoking status, passive smoking, alcohol intake status, physical activity in metabolic equivalents of task hours/day, history of anticoagulation therapy, history of hypolipidemic therapy, history of stroke, history of diabetes, history of hypertension, history of oral contraceptive pill use, parity, age of first birth, age of menopause.