Regarding TDF exposure, twelve, one and one patient(s) received TDF from the first, second and third trimester, respectively. The median duration of TDF exposure during pregnancy was 35 weeks (range: 5-39

weeks). HBV-DNA was assessed at delivery in 12 patients. Among these, 10 patients (83%) had HBV-DNA < 6 logIU/mL at delivery. Two cases of high HBV-DNA were associated with non-compliance and TDF discontinuation at week 9 of pregnancy. The median gestational age at delivery was 39 weeks (range: R788 34-40 weeks). No adverse events related to TDF and no cases of birth defects were observed. Five patients reported breastfeeding, and 3 of them breastfed while receiving TDF treatment without any consequence on the babies up to 1 year. No cases of positive HBsAg were observed in infants. Additionally, among 5 infants with anti-HBs testing, all were anti-HBs positive (84-308mIU/mL). Conclusions: In a HBV real-life cohort, TDF treatment from the first trimester of pregnancy was well tolerated. No cases of MTCT were observed. Moreover, no safety issues were reported for breastfeeding while on TDF up to 1 year. Disclosures: Nathalie Ganne-Carrie – Advisory Committees see more or Review Panels: Roche, MSD; Speaking and Teaching: BMS, Gilead Xavier Causse – Board Membership: Gilead, BMS, MSD, Janssen-Cilag; Speaking and Teaching: Roche, Gilead, BMS, Janssen-Cilag Jean-Pierre H. Zarski – Advisory

Committees or Review Panels: BMS, Gilead, Janssen Cilag, BMS, Gilead, Janssen Cilag; Consulting: Roche, Scherring Plough, Novartis, Roche, Scherring Plough, Novartis; Speaking and Teaching: Siemens Fabien Zoulim – Advisory Committees or Review Panels: Gilead; Consulting:

Roche; Grant/Research Support: Gilead, Scynexis, Roche; Speaking and Teaching: Novartis, Roche, Janssen, Bristol Myers Squibb, Gilead Isabelle Fouchard-Hubert – Speaking and Teaching: JANSSEN Olivier P. Libert – Employment: Gilead Sciences Marie Terrier- Management Position: Gilead Sciences Christiane Stern – Employment: Gilead Sciences Patrick Marcellin – Consulting: Roche, Gilead, BMS, Vertex, Novartis, Janssen-Tibotec, MSD, Boehringer, Pfizer, Abbott, Alios BioPharma; Grant/Research Support: Roche, Gilead, BMS, Novartis, Janssen-Tibotec, MSD, Alios BioPharma; Speaking and Teaching: Roche, Gilead, BMS, Vertex, Novartis, Janssen-Tibotec, medchemexpress MSD, Abbott The following people have nothing to disclose: Ghassan Riachi, Bruno Roche, Hervé Desmorat, Thierry Constant, Jean françois D. Cadranel, Denis Ouzan Background and aim; Non-invasive methods are therefore becoming increasingly important in the assessment of liver histopathology in CHB patients. One of such techniques is LSM performed with transient elastography (TE). In this study we compared pre-treatment liver histology and liver LSM results of CHB patients, and we evaluated the five-year prognostic value of LSM in CHB patients.