Highmark Health is cutting reimbursement to doctors by 4 percent effective April 1 for care provided to patients with health insurance bought through the government exchange — the latest effort to trim losses in a market segment that has caused headaches for carriers nationwide.

All Pennsylvania doctors who participate in Highmark’s health insurance plans and treat patients with coverage required by the Affordable Care Act will be affected by the reimbursement cut, said Alexis Miller, senior vice president of individual and small group markets.

The doctors’ pay cut is needed to stem losses in individual health-law coverage as the insurer looks for other ways to stop the bleeding, Ms. Miller said.