Effects of Radiation on the Embryo and Fetus Lecture 28 Effects of Radiation on the Embryo and Fetus

Intrauterine death Congenital abnormalities and neonatal death Microcephaly, mental retardation Growth retardation Dose, dose rate, and stage in gestation Human experience of pregnant women exposed to therapeutic dose

Three important stages of development Pre-implantation Organogenesis Newly fertilized mouse egg Three important stages of development Pre-implantation Organogenesis Fetal development 3rd day –mouse embryo

Classic effects of radiation on Embryo and Fetus 1. Lethal effects pre-implantation death intra-uterine death neonatal death 2. Malformations Teratogenic effects 3. Growth disturbances Effects depend on: Dose, Stage of gestation and dose rate

Dose= 2 Gy

Intrauterine death Congenital abnormalities and neonatal death Microcephaly, mental retardation Growth retardation Dose, dose rate, and stage in gestation Human experience of pregnant women exposed to therapeutic dose

Congenital malformations (1 Gy)

Irradiation during the period of organogenesis Normal Resorbed fetuses

Irradiation during the period of organogenesis Eye defects

Intrauterine death Congenital abnormalities and neonatal death Microcephaly, mental retardation Growth retardation Dose, dose rate, and stage in gestation Human experience of pregnant women exposed to therapeutic dose

Experience in humans Medical exposures Atomic bomb survivors Effects: Microcephaly CNS defects Growth retardation For period 16-25 weeks Absorbed fetal dose (Rads)

Medical Radiation effects on Embryo and Fetus Less severe abnormalities in human embryo exposed before 2-3 weeks of gestation was observed, although an increase abortion was reported. Severe abnormalities observed between 4 and 11 weeks of gestation. Abnormalities involving eye, skeleton, genital organs and stunted growth, microcephaly and mental retardation was observed between 11 and 16 weeks of gestation. Weeks 16-20 showed mild stunted growth, microcephaly and mental retardation. Irradiation after 30 weeks caused functional disabilites.

Intrauterine death Congenital abnormalities and neonatal death Microcephaly, mental retardation Growth retardation Dose, dose rate, and stage in gestation Human experience of pregnant women exposed to therapeutic dose

Comparison of human and animal data