Background: About 76,000 pregnant women and 500,000 neonates die each year worldwide due to preeclampsia and related hypertensive disorders. In Ethiopia preeclampsia is among the top five leading cause of maternal mortality which causes 11 % all maternal death and 16 % of direct maternal death. Studies on magnitude and associated factors of preeclampsia are limited in southern Ethiopia. The aim of this study was to assess magnitude of preeclampsia and associated factors among mothers who gave birth at Yirgalem General Hospital, Southern Ethiopia.

Methods: Institution based retrospective cross-sectional study was conducted among 361 mothers who gave birth at Yirgalem General Hospital from January 1, 2015 to December 30, 2017. Data was collected from December 1 to 30, 2017 by reviewing medical records of mothers using prepared check list. Logistic regression was performed using SPSS version 20.0 software to identify possible predictors of preeclampsia.

Result: The overall magnitude of preeclampsia was 9.6 % (95% CI; 6.5-12.7). Women who had previous history of preeclampsia [AOR = 3.85; (95 % CI:  1.19 – 12.49)], pre-existing chronic hypertension [AOR = 4.84; (95 % CI: 1.02 - 22.94)], pre-existing renal disease [AOR = 4.91; (95 % CI: 1.42 -16.95)], family history of hypertension [AOR = 7.90; (95 % CI: 2.59 -24.15)] and family history of preeclampsia [AOR = 6.45; (95 % CI: 1.50 -27.76)] were identified predictors of preeclampsia.

Conclusion: The magnitude of preeclampsia in the study area was relatively low compared with other studies in Ethiopia. Previous history of preeclampsia, pre-existing chronic hypertension and renal disease, family history of hypertension and preeclampsia were predictors of preeclampsia. Screening for preeclampsia, improve mothers’ health seeking behavior, follow up of high risk mothers and providing laboratory tests for early diagnosis & initiation of treatments need to be given emphasis.

Key words: Preeclampsia, Associated factors, Yirgalem.