Recommended Waiting Period After Radiation Exposure Before Conception

It is advisable to wait 6 months after doses to the gonads in excess of 100 mGy before attempting conception. 1

Understanding Radiation Effects on Reproductive Health

Radiation exposure to reproductive cells carries a risk of heritable effects estimated at approximately 0.01% affected offspring per 10 mGy (1 rad) absorbed dose to the gonads 1
Animal data suggest that the risk of radiation-induced effects is greatest in the first 2 months after exposure and then declines 1
Studies of atomic bomb survivors show a small but statistically non-significant increase in birth defects in first-generation offspring 1
Recent research indicates that exposure to preconception CT imaging may be associated with higher risks for spontaneous pregnancy loss and congenital anomalies 2

Doses to the gonads in excess of 100 mGy warrant a 6-month waiting period before attempting conception 1
For lower doses (below 100 mGy), the risk of transferring effects to future generations is small 1
Uterine radiation doses of less than 4 Gy do not appear to impair uterine function 3
Noncancer health effects have not been detected at any stage of gestation after exposure to ionizing radiation of less than 0.05 Gy (5 rad) 4

Interventional cardiac procedures typically do not expose the gonads to significant direct beam radiation 1
Scatter radiation to the gonads when the primary beam is focused on the thorax is very small and not affected by external shielding 1
Pelvic procedures place the gonads directly in the X-ray beam and may deliver significant doses to reproductive cells 1
The risk observed with head CT is not consistently lower than with CT of the abdomen, pelvis, or lower spine 2

The principle of ALARA (As Low As Reasonably Achievable) should be applied to protect future generations 1
Effective ways to manage exposure to the gonads during radiography include:
- Keeping exposure duration times to a minimum 1
- Collimating to the area of interest during pelvic radiography 1
- Using appropriate shielding when possible 1

For pregnant women, the dose to the fetus from occupational exposure should not exceed 0.5 rem (5 mSv) over the entire pregnancy and 0.05 rem (0.5 mSv) during any single month 1
The fetus is most susceptible to radiation during organogenesis (2-7 weeks after conception) and in the early fetal period (8-15 weeks after conception) 4
Doses to the conceptus in excess of 50-100 mGy place the child at risk for growth retardation, malformation, resorption, or miscarriage 1
Fetal doses below 100 mGy should not be considered a reason for terminating a pregnancy 5

Women who adhere to recommended radiation safety precautions should feel reassured their exposure will not endanger their future children 1
Personal monitoring with film badge or dosimeter is indicated for pregnant workers who may receive significant radiation exposure 1

A common misconception is that all radiation exposure is equally harmful regardless of dose - in reality, there are threshold doses for most adverse reproductive effects 6
Lack of knowledge about radiation risks can lead to unnecessary anxiety and potentially unnecessary termination of pregnancies 5
For most properly performed diagnostic procedures, the prenatal doses present no measurably increased risk over background incidence of adverse outcomes 5
The relationship between dose to the patient and dose to the conceptus is frequently misunderstood - procedures involving structures above the diaphragm are unlikely to deliver dangerous doses to the conceptus 1