As the third open enrollment period winds down on the health insurance marketplaces, one thing hasn’t changed much since the online exchanges opened: It’s still often hard to find out whether a plan covers abortion services.

The health law requires a plan to say one way or the other, and both antiabortion advocates and abortion-rights proponents say that insurers have gotten better about reporting details. But the federal government has yet to put out final instructions on how insurers should handle the issue on their summary of benefits and coverage overview. Lacking specific instructions about what to say and where to say it, many insurers have simply left the information out of the summary, advocates on both sides of the issue said.

That leaves consumers who have a preference — because of their views on abortion or concerns about need for the service — in a bind. “It’s not easy to figure out whether a plan covers abortion, and, if it does, to what extent,” says Kinsey Hasstedt, a public-policy associate at the Guttmacher Institute, a reproductive health research organization that supports abortion rights.

The health law lets states decide whether marketplace plans can cover abortion services. Half of states ban abortion coverage to some extent, often limiting it to cases of rape or incest or where the mother’s life is endangered. (The federal government uses this standard in its employees’ plans and for health-care programs such as Medicaid.)

However, even in states that permit insurers to cover abortion beyond the limited exceptions, marketplace plans may not offer that benefit.

The lack of easily accessible information makes it hard to know whether the number of plans that provide abortion services on the exchanges is increasing or decreasing.

Advocates on both sides of the issue have their eyes on multi-state plans. The health law called for multi-state plans that would be offered in every state by some insurers. Every state marketplace was supposed to have two multi-state plans by 2017, at least one of which excluded abortion services. In subsequent guidance, the Office of Personnel Management, which administers the multi-state program, said that multi-state insurers had to offer at least one silver-level and one gold-level plan that excludes abortion coverage starting this year.

But the multi-state-plan program is struggling. The number of states where multi-state plans were offered dropped to 32 plus the District in 2016, down from 35 last year.

In those states, most multi-state plans don’t cover abortion. Of the 261 multi-state plans available in 2016, just four plans in two states — Connecticut and Alaska — provide abortion services, according to OPM.

However, abortion opponents said that because multi-state plans aren’t yet available in every state, there’s no guarantee that consumers can find a plan that doesn’t cover abortion.

Abortion-rights supporters have a different beef with the multi-state-plan program. They say it’s not fair to require the marketplace to offer plans that exclude abortion without also requiring plans that include abortion coverage. They also take issue with OPM’s decision that insurers must offer two multi-state plans that exclude abortion coverage, instead of the single one that the law requires.

OPM isn’t considering any changes to the program at this time, a spokesman said.

Advocates on both sides hope that the final instructions for the coverage summaries will make it easier for consumers to learn whether plans cover abortion.

Advocates on all sides agree that the language describing abortion services needs to be clear and consistent rather than the mishmash of descriptions that appear in current documents, where it may be called “interruption of pregnancy” or “elective termination of a normal pregnancy,” among other terms.

This column is produced through a collaboration between The Post and Kaiser Health News.