Objective: To investigate the vertical transmission of hepatitis B virus (HBV) via embryos to children and whether HBV in embryos has an effect on the development of the fetus and pregnancy outcomes of in vitro fertilization and embryo transfer (IVF-ET). Design: Long-term follow-up study. Setting: Research laboratory. Patient(s): Thirty-one couples with a hepatitis B surface antigen (HBsAg)-negative woman and HBsAg-positive man, and 41 couples with a HBsAg-positive woman and HBsAg-negative man, whose unfertilized oocytes and nonviable embryos were tested for HBV DNA, RNA, or HBsAg. Intervention(s): HBV DNA, RNA, or HBsAg analyses in unfertilized oocytes and nonviable embryos. Main Outcome Measure(s): HBV serologic markers analyses. Result(s): We obtained follow-up data for 71 couples. A total of 24 babies were born, and no newborns exhibited defects at birth. Twelve babies were born to couples with HBV-positive oocytes and/or embryos. The pregnancy outcomes were not associated with the presence of HBV in oocytes and embryos. Three patterns of HBV serologic markers were screened. Twenty babies were anti-HBs-positive. Three babies were negative for HBsAg, antibody to hepatitis B surface antigen (anti-HBs), antibody to hepatitis B core antigen (anti-HBc), HBeAg, and antibody to hepatitis B e antigen (anti-HBe). One baby was seropositive for anti-HBs, anti-HBc, and anti-HBe at 6 months of age but seroconverted from anti-HBe-positive to anti-HBe-negative at 9 months of age. Conclusion(s): The presence of HBsAg in oocytes and embryos may not result in the vertical transmission of HBV in the offspring of HBV carriers. (C) 2016 by American Society for Reproductive Medicine.