Citing a commitment to making the U.S. immigration system more “humane,” the Biden administration announced Friday that it barred Immigration and Customs Enforcement (ICE) agents from detaining pregnant or nursing women, absent “exceptional circumstances.” “Given the unique needs of this population, we will not detain individuals known to be pregnant, postpartum or nursing unless release is prohibited by law or exceptional circumstances exist,” said Tae Johnson, the interim head of ICE. “This reflects our commitment to treat all individuals with respect and dignity while still enforcing our nation’s laws.” Johnson had issued a directive to his deportation agents earlier this month establishing the new restrictions, which are part of a broader Biden administration effort to reverse sweeping Trump-era deportation policies and narrow who ICE agents should arrest. Earlier this year, Johnson instructed ICE to focus on arresting immigrants with certain criminal convictions, recent border-crossers and foreigners deemed to pose a national security threat. Arrests of immigrants who fall outside these categories now require supervisory approval. Johnson’s directive this month also requires detention officers to release pregnant or nursing women, unless any of the limited exceptions apply. Pregnant women, the directive said, can only be arrested and detained if they are determined to pose a national security threat or an “imminent risk of death, violence, or physical harm to any individual.” ICE is also restricted by law from releasing immigrants who were detained because of certain criminal convictions or terrorism charges. If ICE decides to detain pregnant or nursing immigrants, they must be provided adequate mental health and medical services, Johnson said. Restraints should also not be used on them, barring limited circumstances, the directive said. As of Thursday, ICE was detaining 13 pregnant women, most of them mothers held at temporary holding facilities for migrant families with children. Nearly 4,000 pregnant women have been arrested and detained by ICE since fiscal year 2017, according to agency data provided to CBS News. The highest number of arrests occurred in fiscal year 2018, when ICE detained 1,459 pregnant women. While ICE arrests have been curtailed under President Biden, the agency’s detainee population has ballooned since the start of his administration, as border officials transfer more migrants to detention centers in the interior of the country. As of last week, ICE was detaining more than 27,000 people, an 82% increase from late January. Eunice Cho, an American Civil Liberties Union (ACLU) lawyer who monitors conditions inside ICE detention centers, applauded Friday’s announcement, saying it could pave the way for “more humane treatment” of immigrant women. But she said the agency could enact additional reforms. “ICE should stop detaining or arresting people who would be at particular risk in detention, must implement robust oversight of detention facilities, and ensure the release of all people who would be particularly vulnerable in detention,” Cho said.