The lethal effect on an unborn child from ionizing radiation is most likely to occur during which stage of pregnancy?

The lethal effect on an unborn child from ionizing radiation is most likely to occur during which stage of pregnancy?

• A. Organogenesis period
• B. Fetal period
• C. Pre-implantation period
• D. Post-implantation period

Answer: (C)

The main idea is that sensitivity to ionizing radiation varies with developmental stage, and the earliest stage carries the highest chance of embryonic death. During the pre-implantation period (roughly the first week or two after conception), the embryo is a small cluster of rapidly dividing cells. A single radiation event can damage or destroy enough cells to prevent the embryo from developing or implanting, leading to pregnancy loss. If the embryo does survive this stage, radiation effects in later periods are more likely to cause malformations or growth issues rather than outright lethality. So, lethal effects from radiation are most likely during the pre-implantation period.

The main idea is that sensitivity to ionizing radiation varies with developmental stage, and the earliest stage carries the highest chance of embryonic death. During the pre-implantation period (roughly the first week or two after conception), the embryo is a small cluster of rapidly dividing cells. A single radiation event can damage or destroy enough cells to prevent the embryo from developing or implanting, leading to pregnancy loss. If the embryo does survive this stage, radiation effects in later periods are more likely to cause malformations or growth issues rather than outright lethality. So, lethal effects from radiation are most likely during the pre-implantation period.