BOSTON -- Having spent the past seven years in an epic struggle to batter their way into the American bedroom, the Reagan troops have finally decided to try a different militant approach. The administration is aiming now for the doctor's office.

Having spent the same years unsuccessfully attacking the right to privacy, they have shifted strategies there as well. They are now trying to roll right over the right to speech.

In its latest move, the administration is attempting to regulate what it has been unable to legislate: a ban on talking, perhaps even thinking, about abortion. They have ruled that the 4,000 family planning clinics that serve 4.5 million women will lose their federal funding if they so much as tell a patient about the option to have an abortion and where she might get that abortion.

These regulations, written to go into effect March 3, mean that even if a woman were to ask about abortion, her doctor couldn't answer. Faced with a pregnant woman -- even a seriously ill woman, even a woman with AIDS -- doctors, nurses, counselors can only speak about abortion to condemn it.

''I consider this a profound and troublesome intrusion,'' says Dr. Jack Graham of the American College of Obstetrics and Gynecology. He is echoing the sentiments of many of his colleagues who never thought they'd have to reserve a chair for the government in their office.

Struggling for an analogy, he adds, ''It is as if a patient came in with an ulcer and we were only allowed to tell him about one treatment.'' The new rules are, he believes, not only an infringement of free speech. They are a mandate for malpractice and a violation of informed-consent laws. ''How can a woman give informed consent to her treatment without getting information?''

On these grounds and others, the ''Reagan Regs'' are now being fought in federal district courts. Last week the sites were Boston and Denver. This week it's New York.

At least one of these courts is expected to acknowledge that the regulations violate the intent of Congress when it funded the clinics under Title X. In voting money, as Rep. Bill Green has said, they did so on the grounds of ''requiring clinics to inform women of all their options.'' An injunction by any of these courts would stop the rules from going into effect until the case is heard in a higher court.

But whatever neat legal language is laid over this subject, it doesn't take a field commander to notice that the administration has turned to guerrilla tactics.

The Reagan right hasn't had a straightforward victory against abortion. The pro-life constituency hasn't won a constitutional amendment or a ban. As a movement, their goals have changed from trying to make abortion illegal to trying to make it impossible. This move is part of that strategy.

The only legislative wins have come when Congress has decided to appease right-to-lifers by yielding up the poor or the Third World. One of the ironies of the current battle is that the family planning clinics under attack by the Reagan Regs are already forbidden to perform abortions. What they offer is birth control to poor women.

I am afraid that the poor have proved to be an easy target, especially for an administration in need of an easy hit. In a bizarre escalation of hostilities, the government now threatens these clinics: say the word ''abortion'' and we will take away the money you are using to help prevent the unwanted pregnancies.

I doubt very much that the rules will survive the court tests. If they do, the government could write the script for every patient consultation.

But it's worth noting how this protracted battle has moved. In the eighth year of the Reagan administration, the attack on the right to choose freely has expanded -- without a single extra regiment -- into a full-fledged attack on the right to speak freely.