From the Indiana Department of Health:
Today, more than 75 percent of women in the United States begin breastfeeding, but the most frequent time for a woman to stop breastfeeding is when she returns to work. Women with children are the fastest-growing segment of the work force, and balancing work and family is an important priority for them. It is important for returning mothers to be in a work environment that provides adequate space and time for them to express their milk during the work day. This allows a woman to continue to give her best efforts at work and for her baby.