The Trump administration announced that government scientists can no longer use human fetal tissue in medical research, reports The Associated Press. The tissue has played a pivotal role in research on HIV and childhood cancers.

Specifically, a federal contract with the University of California, San Francisco (UCSF) will not be extended, according to a statement from the Department of Health and Human Services.

A team of researchers at the university has helped test nearly all HIV treatments approved by the Food and Drug Administration. As was reported in December, that work was being audited and its funding was in jeopardy. Stem cell researcher Irving Weissman said at the time that using fetal tissue was “absolutely essential.”

The HHS statement countered that sentiment. “Promoting the dignity of human life from conception to natural death is one of the very top priorities of President Trump’s administration. The audit and review helped inform the policy process that led to the administration’s decision to let the contract with UCSF expire and to discontinue intramural research—research conducted within the National Institutes of Health (NIH)—involving the use of human fetal tissue from elective abortion. Intramural research that requires new acquisition of fetal tissue from elective abortions will not be conducted.”

The new government policy will not apply to privately funded research.

Scientists have pointed out that the fetal tissue comes from elective abortions and that the research does not increase abortions. They also stressed that they have no alternatives to the human fetal tissue.

The White House’s move is supported by anti-abortionists who, as the AP underscores, make up an important part of Trump’s base. Banning the National Institutes of Health (NIH) from using human fetal tissue has been a longtime goal of abortion opponents.