The Montgomery County school board voted early today to keep instruction on contraception out of the eighth grade, maintaining it at the high school level.

The instruction, given this year as an experiment to eighth graders in three schools, had drawn vigorous opposition from conservative and religious groups and was a focus of controversy second only to that which attended the board's school-closing decisions last fall.

The 5-to-2 vote, part of an overall resolution to approve a revised curriculum on health education instruction for all grade levels, was a victory for the board's conservative majority, which argued that pregnancy prevention was an inappropriate topic for eighth graders.

School board member Marian Greenblatt produced statistics from the county's Commission on Children and Youth that showed that only 4/100ths of one percent of Montgomery County children between 10 and 14 are sexually active and only 1/10th of one percent in the same age range had abortions between 1977 and 1980.

"Should this be the driving force to move this instruction from the 10th to the eighth grade? The answer is no . . . . We should keep this section at the senior high level, not at the eighth grade," said Greenblatt.

Board member Carol Wallace said: "No unit on contraception should be taught at eighth grade. I can't accept it."

Only board members Blair Ewing and Elizabeth Spencer voted against keeping the contraception unit out of the eighth grade.

Since last February, 677 students have taken the two-day unit on contraception as part of a six-week pilot course at Redland Middle, Pyle Junior High and Westland Intermediate schools. The vote eliminated the possibility that the instruction would be provided to all eighth graders.

Members of Citizens United for Responsible Education, a group that has also questioned the way that sex education instruction materials are selected, passed out signs saying "NO Jr. High Contraception" to a standing room only crowd in the board's meeting chamber in Rockville.

They were opposed by a number of vocal citizens who were in favor of the pregnancy prevention unit and by school Superintendent Edward Andrews.

Andrews noted that in a survey a majority of the parents and 324 of 371 students were found to think that contraception information should be taught at the eighth grade level or earlier.

"The topics of reproduction, birth and sexually transmitted diseases have been available to students and have been taught successfully as a three-week unit in physical education classes in eighth grade since the early sixties," he said.

On the other side, Dr. Olga Fairfax, founder of United Methodists for Life argued that "a vote for contraception instruction in the eighth grade is a vote for fornication," adding her belief that illegimate pregnancies and abortions would rise among the young as a result.

Paul Zarod, the parent of a Redland Middle School student who took the course, said that "if school is a place where they can get the stright facts: do it! It's resulted in a sharing of facts at home and intelligent conversation."

By a 5-to-1 vote, with board member Blair Ewing abstaining, the board passed the revised kindergarten-through-12th-grade health education curriculum that is designed to sharpen the objectives of health education and improve and expand instruction about substance abuse, nutrition, safety and sex.

On a motion by board member Joseph Barse, the board voted 5 to 2 to eliminate from the curriculum a sex education film strip called "Teen-Age Pregnancy Prevention" that Barse said would only reinforce the idea that premarital sex is acceptable if one uses contraceptives.

The board also voted to require approval of sex education materials by six members of a citizen advisory panel instead of three, as is now the case.