The Loudoun County School Board last week listened to arguments for and against a proposal to expand its sex education program.

For more than a year the board has been wrestling with the issue of expanding its family life classes, which include sex education, from three high schools to four and offering them to grades six through 10. Groups on both sides of the issue have addressed the board and according to board Chairman Warren Braham, "We are trying, in all of this, to find some middle ground."

The courses, offered to juniors and seniors on an elective basis and with parental permission, are taught as part of the home economics curriculum and include information on budgeting and family relationships as well as sex. Because it is offered through home economics, usually only girls take the course, officials said. The proposed changes would not only expand the sex education curriculum to give more detailed information but would move it into the social studies curriculum to encourage boys to enroll.

In addition, the proposal by superintendent of instruction Harry Bibb would offer a modified version of the course to sophomores and freshmen and would give sixth and seventh graders detailed instruction on human reproduction in their science classes. Nothing has been proposed for the eighth grade.

Speaking against the proposed guidelines on behalf of Concerned Parents, a group formed to oppose the issue, Malcolm Lawrence warned the board of what he considers the moral, legal and medical dangers of sex instruction. Such instruction, said Lawrence, would lead to hostile relations with the community, would open school doors to hustlers of sex devices and lead to premature occupation with sex matters. "It could expose the children to risks of pregnancy and venereal diseases including herpes and AIDS," Lawrence said.

Morris and Winnie Nix, two other members of the Concerned Parents group, said they believe that teaching about sex without including a value system is the same as teaching "no values at all." The group plans to present the board a petition with the signatures of several hundred persons opposing the guidelines Aug. 13, Morris Nix said.

Loudoun Citizens Against Teenage Pregnancy, a group that formed two years ago when its members became aware that there were 200 teen pregnancies in Loudoun County annually, told the board earlier that, while sex education does not guarantee a lower teen pregnancy rate, it can clarify sex issues that concern adolescents. "Teen-agers need to know about contraceptives, venereal diseases or choices in sexuality," said group spokeswoman Theresa Beeton. "Sex education won't solve all our problems but it can help to end confusion."

Some school officials believe it is impossible to teach about sex without injecting morality. One of those is Braham. "My wife and I taught our children about sex ourselves," Braham said. "I don't know the teacher who will be handling these classes and I don't know what his or her morals are. Whatever they are I don't want them imposed on my kids or on other people's kids."

He will do everything in his power, Braham said, to bring the issue to a vote next month. "We can't continue to tear this county apart." Phone calls and letters he has received over the last year lean heavily against the proposal, Braham said.

Board member Betty Peohlman said the majority of her constituents are in favor of the expanded courses. "There have been so many people parading in front of the board," said Peohlman, who favors the proposal. "It's been valuable but exhausting. Now we owe it to the public to decide."