Several federal efforts to combat human trafficking in the U.S. have slowed under the Trump administration, according to government data and human trafficking advocates.

Why it matters: There are thousands of trafficking victims in the U.S. — including children trafficked into prostitution as well as agricultural and domestic workers who are paid little or nothing. But the Trump administration has cut back on prosecutions of these crimes and assistance to victims.

By the numbers: Last year, the National Human Trafficking Hotline identified almost 15,000 people who were most likely trafficked. That's more than any year since at least 2012.

But prosecutions are down: The number of defendants charged with human trafficking by federal attorneys fell to 386 last year, from 553 in 2017, according to the State Department's annual Trafficking in Persons (TIP) report.

The number of defendants charged with human trafficking by federal attorneys fell to 386 last year, from 553 in 2017, according to the State Department's annual Trafficking in Persons (TIP) report. So far this year, federal attorneys have prosecuted 39% of the cases referred to them with child sex trafficking as the lead charge, according to data collected by Syracuse University. That's down from 49% in the last year of the Obama administration.

federal attorneys have prosecuted 39% of the cases referred to them with child sex trafficking as the lead charge, according to data collected by Syracuse University. That's down from 49% in the last year of the Obama administration. Investigations are also down: In 2018, the Justice Department opened just 657 trafficking investigations — down from a spike of 1,800 in FY 2016, per the TIP reports.

Yes, but: Trafficking convictions are still rising — although that could include some cases that began during the Obama administration, said Susan French, a former federal prosector for human trafficking cases.

And while overall prosecutions are down, DOJ continues to prosecute more cases involving child prostitution.

Between the lines: The number of prosecutions isn't the only factor.

The Trump administration recently made it more difficult for victims of sex trafficking to clear their criminal records.

"The criminal justice system harms victims by saddling them with criminal convictions for crimes they were forced to commit by their traffickers," said Martina Vandenberg, president and founder of the Human Trafficking Legal Center.

A criminal history "often means you're not going to get the housing or you're not going to get the job or whatever else you are attempting to obtain," French said.

Anti-immigrant sentiment has also compounded the problem, as many victims of human trafficking come from other nations.

"When you have a tone coming out of the White House which is strongly anti-immigrant... it has a chilling effect on people coming forward," French said.

Federal officials are also denying more "T visas," which are for trafficking victims who cooperate with law enforcement.

The other side: The Department of Homeland Security increased the number of specialists working with human trafficking investigators by 70% last year, according to the TIP report.