@misc{9269,
  author = {I. Matok and L. Azoulay and H. Yin and S. Suissa},
  title = {Immortal time bias in observational studies of drug effects in pregnancy},
  year = {2014},
  journal = {Birth Defects Res A Clin Mol Teratol},
  volume = {100},
  number = {9},
  pages = {658-62},
  issn = {1542-0752},
  doi = {10.1002/bdra.23271},
}