Radiotherapy is most harmful in which week of gestation:

Ans. (a) 4-16 weekRef. Dutta's Obstetrics 7th ed./ 647RADIATION HAZARDS* Teratogenecity: Diagnostic range of radiation exposure (< 5 Rads) is not associated with any congenital malformation.* Oncogenecity: Dividing cells particularly in first trimester are more sensitive to injury from radiation. Diagnostic radiation with fetal exposure is associated with an increased risk of malignancy.* Genetic damage and intrauterine death* NOTE: radiation during early stage of pregnancy can damage the embroyo. This risk can be minimized by using the "10 day rule". This rule states that: "No women should be exposed to X-Ray for a non-urgent indication outside 10 days from her last period during reproductive period"