BackgroundThe aim of the present study is to estimate the prevalence of unintended pregnancy in fathers with children aged less than or equal to 36 months and evaluate whether unintended pregnancy is associated with depression after controlling for covariates. MethodsWe used data from the Brazilian National Health Survey (PNS) of 2019, a cross-sectional study that comprised a representative sample of residents in private households in Brazil. For the analysis of this study, we selected 30,579 men (> 14 years old) who answered to the Selected Resident questionnaire of the PNS and reported having a biological child (son). Among these 4806 had a child with less than 4 years of age and were used in our analysis. ResultsThe prevalence of unintended pregnancy in this group of fathers with a child ≤ 3 years was 35.0 % (95 % CI 32.6–37.5). In the final adjusted model, the variables associated with depression were: PHQ-9 total score (OR: 1.07, 95 % CI 1.03–1.11, p ≤0.001), a higher father's age (OR 1.01, 95 % CI 1.01–1.02), a higher father's age at birth (OR: 0.92, 95 % CI 0.90–0.94), self-reported black (OR: 3.00, 95 % CI 1.94–4.66), brown (OR: 1.63, 95 % CI 1.25–2.13) or indigenous (OR: 0.22, 95 % CI 0.07–0.69) skin color, lower per capita family income >1 to 2 MW (OR: 1.54, 95 % CI 1.01–2.35), ½ to 1 MW (OR: 2.22, 95 % CI 1.46–3.38) and up to 1 MW (OR: 1.76, 95 % CI 1.19–2.59) and not participating in the partner's prenatal appointments (OR: 2.04, 95 % CI 1.55–2.68). DiscussionIn our study, the prevalence of unplanned pregnancy among fathers of child less than 4 years of age is high, and it is associated with depression. Black and brown self-reported skin color, lower family income and higher father's age are associated with increased risk of unintended pregnancy.