Under the new law, employers must provide nursing breaks and a private, sanitary place where mothers of children younger than 1 who work as nonexempt employees can express breast milk. Salaried women are expected to benefit as well. Companies with fewer than 50 workers may be exempt from the law. Still, the law should benefit the women who may find it hardest to continue to breast-feed after returning to work: lower-income and lower-educated women. Overall, the provisions in the law cover three-fifths of employed women living in families with incomes less than $50,000 a year.

“It is unfair that the health benefits of breastfeeding have been disproportionately available to mothers and children of high socioeconomic status,” the authors of the report, from the Institute for Women’s Policy Research , wrote. “The ACA breastfeeding protections, as well as the additional policies discussed in this report, can help to rectify this situation, and make breastfeeding less a matter of privilege and opportunity and more a matter of unconstrained individual choice for new mothers.”