Is an employer required to reasonably accommodate an employees work schedule relating to child care

My wife works for AT&T and we have 2 young children, I work for a fire department and have a schedule of 24 hours on 48 hours off (I work every 3rd day regardless of holidays). AT&T used to accommodate her schedule reasonably based around how stable mine was, and the fact that I can tell you exactly when I work 5 years from now. A new manager has started with her and refuses to accommodate her reasonable request for scheduling. This now makes it nearly impossible to provide child care needed. Is an employer required to reasonably accommodate an employees need based around child care? This individual created a problem where one did not exist before.