On Friday, the Centers for Disease Control and Prevention purged from its website thousands of pages that included terms such as “transgender,” “L.G.B.T.” and “pregnant person,” to comply with an executive order barring any material that promoted “gender ideology.”

By Monday, some of the pages had reappeared, in part in response to intense media coverage, backlash from the scientific community and concern for the public’s health, according to a senior official with knowledge of the matter.