The Reagan administration would be "acting as a law unto itself" if it proceeds with a proposed regulation that would require notification of parents whose teen-agers receive contraceptives, several House Democrats charged yesterday.

Warning that there "will be more pregnancies among adolescents and more abortions," the House Commerce health subcommittee chairman, Henry A. Waxman (D-Calif.), and others argued that the pending regulation would deliberately disregard the language and intent of a compromise family planning bill passed by Congress last year.

Health and Human Services Secretary Richard S. Schweiker, however, defended the proposal as a legally defensible way to "encourage family involvement" by informing parents when their children are using prescription birth control products.

"Parents must give written permission before a child can go on a school trip and must explain when a child is absent from class for even one day. It is paradoxical that when it comes to prescribing drugs and devices with potentially serious health consequences, federal policy has not recognized parental involvement and responsibility," Schweiker said.

While Waxman contended at the hearing that the proposal was politically motivated, Schweiker maintained that he was acting "not only as a parent but also as the secretary of the federal department responsible for the public's health."

The proposal would require that parents of teen-agers under 18 who receive prescription contraceptives, such as birth control pills, from federally supported family planning clinics be notified within 10 days of that fact. The only exceptions would be when the "project director determines that notification would have adverse physical health consequences for the minor."

An estimated 1.5 million teens each year go to family planning clinics, about 45 percent of them under 18. Nearly 80 percent choose the prescription birth control products that fall under the HHS proposal, which Schweiker said would be issued "in the next several weeks."

Waxman said the language of the bill he wrote says that family involvement should be encouraged "to the extent practical" but that House-Senate conferees concluded that it is "not mandated."

But Schweiker maintained that Sens. Jeremiah Denton (R-Ala.) and Orrin G. Hatch (R-Utah) believed the regulations conformed with the intent of Congress. He agreed with Waxman that the matter was likely to be settled in the courts.

Denton supported the proposal as a "long overdue step" but argued that it did not go far enough in requiring parental consent, a complaint also voiced by several antiabortion groups.

But medical organizations, including the American College of Obstetricians and Gynecologists (ACOG), the American Medical Association, and the American Academy of Pediatrics, backed Waxman's claim that even notification after-the-fact would be a "barrier."

Dr. Luella Klein, of Atlanta's Emory University, said that she was "certain that the health and well-being of millions of young Americans would be severely endangered" by discouraging adolescents from seeking care and thereby increasing the risk of pregnancy.

Rep. Patricia Schroeder (D-Colo.) also attacked the proposal as being unfair to financially strapped young women who need help from clinics, while others could continue to get contraceptives from private doctors without their parents' knowledge.