Pregnancy

Anastrozole is classified as FDA pregnancy risk category X.(12) It is contraindicated for use in women who are pregnant or may become pregnant. Anastrozole may cause fetal harm when administered to pregnant women and offers no clinical benefit when administered to premenopausal women with breast cancer. Animal studies indicate that anastrozole increases pregnancy loss, both pre- and postimplantation. It crosses the placenta and causes fetal harm, including delayed fetal development, but there has been no evidence of teratogenicity. There have been no adequate studies in pregnant women, and anastrozole is only approved for the treatment of postmenopausal women, and should generally not be used in females of childbearing potential. If pregnancy occurs, however, while the patient is receiving anastrozole, she should be warned about the possible risk to the fetus and possible loss of pregnancy.