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If the applicant is pregnant must she have a chest x-ray?
The U.S. Centers for Disease Control and Prevention (CDC) requires that women who are pregnant and required to have a medical examination in connection with the issuance of a visa, and are examined in a country currently using the 2007 TB Technical Instructions must have a chest x-ray examination conducted. Pregnant women will have to provide the panel physician with consent to conduct the chest x-ray. For the health of the applicant and her unborn child, CDC instructs panel physicians and laboratories to provide abdominal and pelvic protection with double layer, wrap-around lead shields when they receive the chest radiographs. This requirement does not apply to countries using the 1991 TB Technical Instructions which allow for an exemption of the chest x-ray requirement for pregnant women. Pregnant applicants who do not wish to have the X-ray will be granted a temporary exemption when they provide written certification of pregnancy signed by their personal physician or obstetrician.
http://www.travel.state.gov/visa/immigrants/info/info_3745.html#_What_if_the_1