Background Anemia during pregnancy is a common public health problem globally and it defined as the hemoglobin concentration of less than 11 g/dl. Anemia during pregnancy has maternal and perinatal diverse consequences and it increase the risk of maternal and perinatal mortality. The aim of this study is to assess magnitude and factors associated with anemia among pregnant women attending antenatal care in Bench Maji, Keffa and Sheka zones of public hospitals, South west, Ethiopia, 2018. Methods A cross-sectional study was employed on 1871 pregnant mothers from selected hospitals. All third trimester pregnant women attending antenatal care at Mizan-Tepi University Teaching Hospital, Tepi, Gebretsadik Shawo and Wacha public hospitals were included in the study. Data was entered to Epidata version 3.1 and exported to SPSS version 21 for analysis. Logistic regression analysis was carried out to identify independently associate factors at confidence interval of 95% and significance level of P-value <0.05. Result The magnitude of anemia in this study from the total study participant was 356 (19.0%). Among anemic pregnant women, 330 (92.7%), 21(5.9%) and 5(1.4%) were mild anemia, moderate anemia and severe anemia respectively. Age group 20–24 [AOR 6.28(2.40–16.42)], 25–29 [AOR = 6.38 (2.71–15.01)], 30–34 [AOR = 5.13 (2.27–11.58) and age ≽35 years [AOR = 2.53 (1.07–5.98)], educational status (read and write) [AOR 2.06, 95% CI (1.12–3.80)], gestational age(term)[AOR 1.94, 95% CI (1.27–2.96)], Caffeine (coffee and tea) and alcohol use occasionally [AOR 2.01, 95% CI (1.14–3.55)] and [AOR 2.59, 95% CI (1.49–4.52)] respectively, nutritional status (under nutrition) [AOR 3.00, 95% CI (2.22–3.97)] and family size (>6) [AOR 2.66, 95% CI (1.49–4.77)] were factors associated with anemia. Conclusion The magnitude of anemia found to be high. Age, educational status of the mother, gestational age, caffeine and alcohol use, Nutritional status and family size were factors significantly associated with anemia. To prevent adverse outcome of anemia, health care providers should work on these factors.
