In pre-implantation embryos (first 9 days after conception) embryos are sensitive to the lethal effects of radiation only (total or no response)
Fetuses in the organogenesis stage (2-15 weeks of gestation) are the most sensitive to the teratogenic effects of ionizing radiation
Even in late gestation, the central nervous system is the most sensitive organ to ionizing radiation.
Prenatal exposure to diagnostic radiation at any stage of pregnancy is usually not a legitimate reason to recommend therapeutic abortion.
Radiation exposure to the pregnant woman and especially to the fetus should be minimized unless the benefits of the test outweigh the risks. Alternative methods (ultrasound) or delaying the test until 105 days of gestation should be considered.
There is no increased risk of macrosomia with intrauterine exposure of less than 5 rads or less than 50 mrads of radiation per month.
Fetal radiation exposure (mrads)
Skeletal X-rays
0.05
Chest X-ray
0.02-0.07
Dental
0.02
Mammography
7-20
Gallbladder uptake
5
Pelvimetry
1000-2000
Barium meal
820-1000