Background <p>Despite an increase in the prevalence of breastfeeding initiation and breastfeeding duration over the past decades in the US, breastfeeding practices remain suboptimal and fall well below the Healthy People 2030 goals. We aimed to investigate the potential associations between socio-demographic factors and breastfeeding initiation and duration, with the goal of identifying factors that act as barriers or facilitators to breastfeeding practices.</p> Methods <p>A total of 7,629 US children aged 0 to 24 months were included from the National Health and Nutrition Examination Survey data between 1999 and 2018. Logistic regression was used to examine the relationship between socio-demographic factors and breastfeeding initiation and duration, with a heat map illustrating their combined associations. Meta-regression was employed to estimate the temporal trends in odds ratios (OR) for the effect of socio-demographic factors on breastfeeding outcomes.</p> Results <p>The overall prevalence of breastfeeding initiation and duration at 3, 6, and 12 months were lower among non-Hispanic Black children [adjusted OR (aOR): 0.42; 95% confidence interval (CI): 0.35, 0.51; 0.77; 0.63, 0.95; 0.58; 0.47, 0.71; 0.45; 0.32, 0.62] when compared with White children, while higher among high-income families (1.53; 1.31, 1.78; 1.24; 1.04, 1.48; 1.36; 1.15, 1.61; 1.23; 0.96, 1.59), mothers older than 25 years at delivery (1.68; 1.45, 1.95; 1.95; 1.63, 2.34; 1.88; 1.58, 2.23; 1.62; 1.26, 2.08), and nonsmoking mothers during pregnancy (2.65; 2.19, 3.21; 2.10; 1.60, 2.75; 2.52; 1.86, 3.41; 1.97; 1.26, 3.07) than among low-income families, mothers aged ≤ 25 years, and smoking mothers, respectively. When stratified by 10 consecutive cycles, the disparities in temporal trends among most socio-demographic factors remained stable, but the gaps among smoking status even widened over time. Heat map analysis further depicted the combined associations between these factors and breastfeeding practices, and found that children born to Black mothers, smoking mothers, mothers aged ≤ 25 years, and low-income families generally had lower odds of breastfeeding initiation and breastfeeding duration at 3, 6, and 12 months.</p> Conclusions <p>Children born to socioeconomically disadvantaged families generally exhibited poorer breastfeeding practices.</p> Clinical trial number <p>Not applicable.</p>