Background: There is rare documentation on the prevalence of gingivitis in pregnancy in the least developed countries. The aim of the study is to evaluate the prevalence of gingivitis in the second trimester of pregnancy and assess its relationship with age, parity, education, occupation, gravidity, oral hygiene habit and frequency of brushing.Methods: An observational descriptive study was conducted among 384 pregnant females in their second trimester in Kathmandu, Nepal. Demographic variables and general information including those related to oral hygiene practices and habits were collected during an interview. Plaque index and Gingival Index was recorded among the patients through full mouth examination at four sites.Results: The prevalence of gingivitis in the second trimester of pregnancy was 76.3%. Statistically significant relationship was found between gingivitis and gravida and parity. A relation could not be established between gingivitis with age, education, occupation, oral hygiene habit and frequency of brushing.Conclusions: The prevalence of gingivitis is found to be high in Nepalese pregnant women. Special strategies should be introduced targetting the pregnant women of least developed countries to uplift their periodontal health.