OZ Objective: Women of childbearing potential treated for chronic hepatitis B virus (HBV) infection may experience exacerbations during or after pregnancy. Infants may also acquire HBV infection through perinatal route. Currently, there is no antiviral agent approved for use in pregnancy. This makes it difficult to decide whether treatment should be withdrawn immediately or continued in women who become pregnant while on HBV antiviral therapy. The present study aims to establish the safety and, as a second measure, the efficacy of telbivudine in patients who became pregnant while they were on telbivudine treatment for chronic HBV infections and were maintained on the treatment throughout pregnancy. Materials and Methods: Between 2010 and 2013, twentyone patients, who became pregnant while receiving telbivudine treatment for chronic HBV infection and continued the treatment, were evaluated retrospectively. Results: The mean age of the patients was 28.9±6.3 years (range: 18-41 years). All patients were hepatitis B envelope antigen-negative. The mean pre-treatment hepatic activity index was 9.4±1.6 (range: 7-13), and fibrosis and serum HBV, DNA measurements were 3.2±0.8 (range: 2-5) and 3.5x105±2.8x105 IU/mL, respectively. No drug-related side effects were seen in any of the patients. All infants had normal birth weights and no abnormalities were observed in any of them. At the end of week 28, none of the infants was hepatitis B surface antigen-positive. Conclusion: The use of telbivudine from the first trimester of pregnancy appears to be safe both for the mother and fetus and Amac: Kronik hepatit B virusu (HBV) nedeni ile takip edilen dogurganlik cagindaki kadin hastalarda kronik karaciger hastaligi gelisebilir, gebelik doneminde veya sonrasinda alevlenmelere neden olabilir, bununla birlikte perinatal donemde HBV bulasi ile bebek infekte olabilir. Gebelik doneminde HBV enfeksiyonu icin kullanimi onaylanmis bir antiviral ilac yoktur. Bu nedenle, antiviral ilac kullanirken gebe kalan kadinlarda tedaviyi sonlandirma ya da devam etme kararini vermek zordur. Bu calismada kronik HBV enfeksiyonu nedeniyle telbivudin tedavisi almakta iken gebe kalan ve tum gebelik donemi boyunca tedavi alan hastalarda telbivudinin ilk etapta guvenilirligini daha sonra ise etkinligini degerlendirmeyi amacladik. Gerec ve Yontemler: 2010-2013 yillari arasinda kronik HBV enfeksiyonu nedeniyle telbivudine tedavisi kullanirken gebe kalan ve tedaviye devam karari verilen 21 hasta retrospektif olarak degerlendirildi. Tum hastalarin tedavi baslandigi andaki serum hepatit B yuzey antijeni, hepatit B zarf antijen, anti-HBe, HBV DNA, alanin aminotransferaz (ALT), aspartat aminotransferaz (AST) seviyeleri, hepatik aktivite indeksi ve fibrozis degerleri kaydedildi. Daha sonra hastalarin gebelik baslangici, gebelik donemi boyunca ve dogum sonrasi 6. aya kadar 3’er ay ara ile serum hepatit B yuzey antijeni, hepatit B zarf antijen, anti-HBe, HBV, DNA, ALT, AST seviyeleri olculdu. Bulgular: Hastalarin yas ortalamasi 28,9±6,3 (yas araligi: 18-41) idi. Tum hastalar hepatit B zarf antijen negatif idi. Tedavi oncesi hepatik aktivite indeksi ortalama 9,4±1,6 (yas araligi: 7-13), fibrozis 3,2±0,8 (yas araligi: 2-5), serum HBV DNA duzeyi 3,5x105±2,8x105 IU/mL idi.