Nutrition during pregnancy is one of the key elements to good maternal and child health, as well as to lifetime landmarks. However, many pregnant women go undernourished in less developed settings. The purpose of this study was to estimate the prevalence and factors associated with gestational night blindness (GXN) and maternal anemia in a cross-sectional population-based study in Cruzeiro do Sul, Acre State, Western Brazilian Amazon. All women living in the municipality admitted at the only maternity-hospital in the city to delivery of a singleton infant were eligible to this study (n = 1,525). Recruitment of participants took place between July 2015 to June 2016. GXN was assessed in the postpartum period by WHO standardized interview. Maternal anemia was defined as hemoglobin at delivery < 110.0 g/L. We estimated prevalence rates and adjusted prevalence ratios (aPR), alongside 95% confidence intervals (95% CI), of the factors associated with the outcomes through multiple Poisson regression models with robust variance. Alarming prevalence of GXN (11.5%; 95% CI, 9.97-13.25) and maternal anemia (39.4%; 95% CI, 36.84-41.95) were found. Factors associated with GXN were (aPR; 95% CI): ≥ 5 residents in the household (2.06; 1.24-3.41), smoking during pregnancy (1.78; 1.15-2.78), and attending < 6 antenatal care visits (1.61; 1.08-2.40). Factors associated with maternal anemia were (aPR; 95% CI): maternal age < 19 years (1.18; 1.01-1.38), gestational malaria (1.22; 1.01-1.49), not taking micronutrient supplements during pregnancy (1.27; 1.01-1.62), and attending < 6 antenatal care visits (1.40; 1.15-1.70). High prevalence rates of GXN and maternal anemia in these postpartum women may reflect poor assistance during antenatal care, underlying the importance of rethinking current protocols related to nutrition in pregnancy.