The Montgomery County public school system is testing a new health curriculum in which methods of contraception are taught in eighth grade classes, the first time such material has been made available to students below high school age.

At the same time, the Montgomery Council of PTAs is planning a series of seminars for parents of adolescents designed to help them talk to their children about sex and the risks of early pregnancy.

Both efforts are in response to national and local statistics about teen-age sexual activity that several community leaders have called "shocking." According to national figures released last year by the Alan Guttmacher Institute in Washington, 40 percent of all teen-agers are sexually active by the time they are 17. In urban areas such as Washington, the number jumps to 70 percent for young people who have reached the age of 19.

One million girls between the ages of 13 and 19 become pregnant every year, reported the institute, a national family planning research and policy organization. In Montgomery County, the number of teen pregnancies is significantly lower among girls 15 to 19 than the national average for that age group--5.5 percent compared to 10 percent nationally--but it is still distressing to parents, teachers and health officials.

"For the past couple of years, we have been bugging the school system to do something," said Zoe Lefkowitz, president of the county PTA council.

Athough she concedes that teaching contraception in the eighth grade may be "controversial," she adds, "Every professional I know feels this is the age it is needed. Something like 50 percent of the students become sexually active right after that (age). . . . I think it's a necessity, as a parent, that . . . they know what they're getting into. And they don't. Girls have this idea they can't possibly get pregnant the first time, and the young men don't care."

The contraception unit--currently offered in the 10th grade--is part of a revised health education curriculum for students in kindergarten through 12th grade being tested in several schools during the semester that starts this week, said Lois Martin, associate superintendent for instruction in program development. If successful, the program will go to the school board for approval late this spring.

Extensive criticism from parents led to the proposed revision of the present curriculum, in use several years, which covers family life and human development, nutrition, drugs, and first aid and safety.

Lefkowitz said that sex education has been taught inconsistently in schools throughout the system under the present program. The PTA council declined a request by County Executive Charles W. Gilchrist to poll parent attitudes toward this program because it contended that instruction varied so widely from school to school that such a survey would be pointless.

"In some schools it (sex education) was not presented very well, if at all," Lefkowitz said.

Last year eighth graders from Pyle Junior High in Bethesda complained to the school board that they would rather take gym than the mandatory sex education course that replaced it. The three-week course, they complained, was too basic and repetitive to be helpful.

Guidelines call for the classes to cover peer relationships, puberty, reproduction, menstruation, fertilization, pregnancy, heredity, birth and venereal disease. But teachers are forbidden to discuss contraception, abortion, homosexuality or masturbation, subjects that the students and many of their parents felt the children needed to be informed about.

In addition, the county Commission on Children and Youth last fall faulted the school system's sex education program, noting that 1979 county figures show that 3.54 percent of all girls aged 15 to 19 in the county had abortions, twice as high as the rate of 1.69 percent for the entire female population.

"The commission really scolded us (the schools) for not doing more," said Martin.

The new eighth grade class, for which students will be required to have parental consent, will be expanded from three to six weeks, she said. It will continue to cover the reproductive system and venereal disease, but material on drug abuse and ways to prevent pregnancy will be added.

"The emphasis will be on coping and decison making, helping students recognize pressures from peers (on both drugs and sex) and dealing with it," Martin said.

How specific the unit on contraception will be is still to be worked out by the teachers, principals and parents at the two pilot schools, Westland Intermediate in Bethesda and Redland Middle School in Rockville, Martin said.

The entire new health curriculum, most of which is mandated by the state, has been made much more specific, Martin said. The current program gives broad objectives that students must master by specified grade levels, but what has happened in the past, particularly in elementary school, was that "everybody expected everybody else to do it," she added.

Under the revised program, teachers will be given detailed instructions on what should be taught in each grade. The elementary curriculum will be piloted in five schools: Fox Chapel in Germantown, Stedwick in Montgomery Village, DuFief in Potomac, and Damascus and Poolesville.

The new fifth-grade course will include a study of human reproduction. Parents will be invited to school to see the materials that will be taught and may request that their children not be included.

The response to the new sex education program in light of a growing conservative mood in the county is uncertain. During the mid-1970s, when the state first mandated much of the present sex education curriculum, a group of Montgomery parents sued to abolish parts of it. A settlement, which took five years to reach, resulted in stricter guildelines for what could be taught and a requirement that parental permission be obtained before students attended the classes.

The school staff has tried to be very careful about consulting parents and health officials in designing the new program, Martin said, "and I hope all the work so far will be acceptable to the community."

PTA President Lefkowitz said she hopes the new curriculum will not revive opposition to sex education in the county, "but I wouldn't be surprised if it did."

"I hope the school board will understand the problems of preadolescence and take a strong stand in favor of this program," she added.

On its own initiative, the PTA council is exploring the possibility of sponsoring a series of seminars devised jointly by the March of Dimes and the national Congress of PTAs.

"The program was developed for parents who want to talk to their children about sex but don't have the information or the ease," said Dr. Carol Gregg, director of public education for the Center for Population Options and a volunteer adviser for the program.

At the seminars, usually held in local schools, parents of students from seventh to 12th grade discuss real case histories and explore their own values toward teen-age sexual behavior.

"There is no effort to force any values," Gregg said. "The goal is to have parents go home and share their values with their children."

The program was initiated by the March of Dimes, Gregg said, because of the rising number of infant deaths and birth defects now linked to adolescent pregnancy. According to Gregg, infant death is twice as frequent among babies of teen-agers as among babies of mothers in their 20s. In addition, mothers who are 15 or younger are twice as likely to have babies with low birth weight, the greatest cause of neurological abnormalities.

Lefkowitz said she will ask the PTA council's executive committee to approve the program this week. The seminars for parents would be held later this year.