BackgroundGestational weight gain is an important factor that supports optimal outcome for mothers and their infant. Whereas women who do not gain enough weight during pregnancy have a risk of bearing a baby with low birth weight, those who gain excessive weight are at increased risk of preeclampsia and gestational diabetes. Nonetheless, data on gestational weight gain and its determinants are scarce in developing countries, as it is difficult to collect the information throughout the pregnancy period. Therefore, the aim of the study was to assess weight gain during pregnancy and its associated factors.MethodsThe study employed a health facility based quantitative cross-sectional study design in Harari Regional State. The study included 411 women who had given birth at health institutions from January to July of 2014. The researchers collected both primary and secondary data by using a structured questionnaire and a checklist. Using logistic regression, the factors associated with gestational weight gain were assessed and, based on the United States Institute of Medicine criteria, gestational weight gains were categorized as inadequate, adequate and excessive.ResultsThe study revealed that 69.3 %, 28 %, and 2.7 % of the women gained inadequate, adequate and excess gestational weight, respectively. The mean gestational weight gain was 8.96 (SD ±3.27) kg. The factors associated with adequate gestational weight gain were body mass index ≥ 25Kg/m2 at early pregnancy (AOR = 3.2, 95 % CI 1.6, 6.3); engaging in regular physical exercise (AOR = 2.1, 95 % CI 1.2, 3.6); Antenatal care visit of ≥4 times (AOR = 2.9, 95 % CI 1.7, 5.2); consuming fruit and vegetable (AOR = 2.7, 95 % CI 1.2, 6.6), and meat (AOR = 2.7, 95 % CI 1.1, 97.2).ConclusionsGenerally, a small proportion of the women gained adequate gestational weight. The women who were with higher body mass index at early pregnancy, who frequently visited Antenatal care visit, and who consumed diverse food items were more likely to measure adequate gestational weight.