Health insurance giant Aetna reported first-quarter net losses of $381 million Tuesday, attributing results primarily to the termination of its proposed $37 billion deal with Humana.

The merger was blocked last year following a Department of Justice antitrust lawsuit filed under former President Barack Obama, which resulted in Aetna paying Humana $1 billion in break-up fees for ending the deal.

Aetna received backlash from Obamacare supporters last year when it exited most of the exchanges in states it participated in, and the company's Chief Executive, Mark Bertolini, has said Obamacare is in a "death spiral."

The federal judge who decided the antitrust case wrote in his opinion that Aetna appeared to reduce its exchange participation as backlash against the Obama administration's attempt to block the merger, but Aetna has maintained its decision was based on $450 million in losses it suffered on account of its Obamacare participation last year.

Aetna has already announced its intention to leave the Obamacare exchange in Iowa, and during an earnings call Tuesday would say only that it was continuing to evaluate what its participation would be for next year.

"We intend to communicate other 2018 decisions when appropriate," Bertolini said.

Though outside experts say the exchanges have stabilized, some insurers say they have lost money through the program and have fled the exchanges in some states, reducing options for customer and resulting in higher premiums.

Insurers are facing uncertainty under the Republican-led Congress, which has vowed to repeal and replace Obamacare, as well as under President Trump, who will not commit to continuing over the long term to pay out Obamacare funds that help insurers lower out-of-pocket medical costs for customers.

Aetna executives said Tuesday that its exchange customers continue to have more high-cost medical needs, but its other government-backed products through Medicare and Medicaid have resulted in strong revenue. For the first time, the company's government business premiums have exceeded commercial premiums.