I noticed that the information presented on the internet is often complex so here I will try to break it down simply by stages.
First Trimester:
When discussing the sensitivity of the embryo-fetus, I am referring to effects that occur in utero.
Because embryonic cells begin dividing and differentiating after conception, they are extremely radiosensitive (sensitive to radiation;x-rays) and hence are much more easily damaged by exposure to radiation.
The most crucial stage of pregnancy to avoid radiation would be during the first trimester.This is a concern due to the embryo-fetus containing a very large number of stem cells. Stem cells are incredibly important because these cells can differentiate into specialized cells AND can self-renew- basically if these are damaged, they can never be replenished and therefore breed death to those cells - not good.
The central nervous system and related sense organs contain many many stem cells and are therefore susceptible to radiation-induced damage. Frequently If the embryo is exposed to approx. 20 rem (measurement for radiation) in the first 8 weeks of development results in death or causes congenital abnormalities.
But please do not let that scare you, the average exposure in an abdominal x ray = 0.07 rem and if you have a CT scan, it is only about 1 rem. However, it is important to be cautious of the studies and doses of radiation that you'd be receiving It is the responsibility of the clinic or hospital to ask you if you are pregnant before administering radiation dose, however if you are not sure I would recommend that you get a blood pregnancy test - don't risk it!
In the first 0-9 days, or the preimplantation days, the fertilized ovum divides and forms a ball-like structure containing undifferentiated cells. If this specific structure is irradiated (exposed to radiation) with a day of 5-15 rem, embryonic death will occur. 5 rem is definitely achievable if you are having a dynamic test of many organs/bones/whole body scans. Again, If you are scheduled for any ionizing radiation exam and are unsure of pregnancy, do not risk it, confirm pregnancy before moving forward.
10 days-8 weeks:
10 days to 8 weeks after conception, the developing fetus is most susceptible to radiation induced abnormalities. This is when the cells are beginning to differentiate into organs. The central nervous system in the human fetus does not complete development until approx. the 12th year of life so it's important that we try not to disrupt the body's natural chemistry. The abnormalities that occur as consequence of radiation during this period of development can include growth inhibition, mental retardation, microcephaly, genital deformities, and sense organ damage. During the later part of this stage, around 8 weeks, the presence of fatal abnormalities in the fetus will cause neonatal death (death at birth). High doses of radiation also will cause death to occur. This is serious stuff people, and important for you to know!
Side note: Skeletal damage from radiation exposure occurs most frequently during week 3-20 of pregnancy.
Second and Third Trimester:
If exposure to radiation is crucial to baby or mommy survival, the BEST stage to be exposed to a reasonable dose of radiation is the 2nd trimester, this is because fetal radiosensitivity decreases as gestation progresses. However, cancer, congenital abnormalities, and functional disorders such as sterility may be caused by radiation exposure during these last trimesters.
I presented this information not to scare you, but to make you aware. Believe me, radiation exposure dose is highly regulated by the government in hopes to prevent any biologic harm. The above information pertains mostly to an OVER EXPOSURE of radiation, so don't be worried to get a chest or abdomen x-ray during pregnancy, but be aware of how far along you are in your pregnancy and CONSULT your doctor if you are concerned. Most facilities have standards that will not allow a mother in specific stages to be radiographed but don't always trust your medical system; there are some states that do not share the same regulatory standards as others and your technician could be under educated and improperly trained. Check with your state health department if you are concerned.
For more information, references, or questions leave a comment!
