Pregnancy Radiation Effects

Solomon Oyakhire
March 22, 2021

Submitted as coursework for PH241, Stanford University, Winter 2021


Fig. 1: Effects of the atomic bomb on Hiroshima.(Source: Wikimedia Commons)

Direct exposure to radiation causes tissue damage and greatly increases the risk of cancer in humans. [1] While the effect of radiation exposure is not trivial for humans, fetuses carried by humans are affected to varying degrees depending on a variety of factors, some of which include the amount of radiation that the human carrying the fetus is exposed to and the extent of development of the fetus. [2] Here, we discuss the effects of radiation exposure on pregnant people that are exposed via a variety of avenues, and by drawing from the literature, we provide quantitative estimates of the amounts of radiation considered unsafe for the pregnant person and the possible side effects of excessive radiation.

Effects of Radiation on the Fetus

Some research studies have been based on radiation exposure associated with atomic bombs like the Hiroshima incident. [2] However, studies that are based on instances like Hiroshima are limited by the concurrent destruction of research and medical facilities. Fig. 1 shows the extent of destruction in Hiroshima after the atomic bomb detonation. Results from the Hiroshima exposures indicate that of the >2800 pregnant women that were exposed, 500 of their fetuses absorbed about 10 mGy of radiation. [3] While certain detrimental effects were observed in the children born by women exposed to radiation, many questions have revolved around whether the effects can be solely attributed to the radiation absorbed by the pregnant women. To control for the numerous external factors associated with radiation absorption, subsequent studies on the effect of radiation on the fetus have been derived from human exposures to diagnostic and therapeutic radiation. [3]

The effects of radiation on the fetus depends on the fetal period and the magnitude of doses during exposure. It has been established that risks are most significant in the early fetal period and least significant in the third trimester. [3] One study performed on 50 pregnant women who underwent radiologic examinations estimated absorbed radiation to be between 0.01 μGy and 117 mGy with gestational ages between 2 and 24 weeks. [4] Other authors stated that fetal exposure of 1000 mGy may cause mental retardation and increase the risk of childhood cancer. [3,5] Based on their results, they concluded that diagnostic radiation in controlled amounts pose small risks to the fetus. In a complementary report, another study showed that the fetus is most sensitive to radiation between the 8th and 15th week of gestation. [6]

Controlling exposure to radiation is easier to handle for someone that is aware that they are pregnant. Early pregnancy exposures are also a cause for concern because research suggests that radiation exposure in the period < 2 weeks before gestation could be detrimental for the fetus. Specifically, an exposure of 100 mGy could lead to the death of an embryo before pregnancy becomes suspected. [3] This is especially important for female radiological center operators. As such, they must receive educational training regarding the potential risks of exposure and the ways in which they can limit their exposure risks.


Many considerations come into play when factoring pregnancy into exposure to radiation. Because of the intricacies associated with radiation absorption in pregnant people, it is critical to rigorously train physicians on the deleterious effects of radiation on the fetus, educate pregnant people on the risks associated with processes that involve radiation, and institute safe radiation practices.

© Solomon Oyakhire. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.


[1] W. J. Schull, "The Children of Atomic Bomb Survivors: A Synopsis," J. Radiol. Prot. 23, 369 (2003).

[2] Y. Yoshimoto, "Cancer Risk Among Children of Atomic Bomb Survivors," J. Am. Med. Assoc. 264, 596 (1990).

[3] P. Shaw et al., "Radiation Exposure and Pregnancy, " J. Vasc. Surg. 53, 28S (2011).

[4] E. K. Osei and K. Faulkner, "Fetal Doses from Radiological Examinations, " Br. J. Radiol. 72, 773 (1999).

[5] H. Yoshimaru et al., "Effect on School Performance of Prenatal Exposure to the Hiroshima Atomic Bomb," Japanese J. Hyg. 46, 747 (1991) [in Japanese].

[6] H. B. Kal and H. Struikmans, "Pregnancy and Medical Irradiation; Summary and Conclusions from the International Commission on Radiological Protection, Publication 84," Ned. Tijdschr. Geneeskd. 146, 299 (2002) [in Dutch].