On the premise that teen-agers who regularly attend religous services are less likely to get pregnant, Planned Parenthood of Metropolitan Washington gathered religious leaders of all stripes recently to help devise ways to increase teen church attendance.

Catholics, Presbyterians, Christian Scientists, Baptists and Moslems, among others, met at National City Christian Church on Thomas Circle for the first religious leaders' training conference sponsored by Planned Parenthood.

"Statistics tell us that teens who attend church on a regular basis are less likely to get pregnant than those who don't," said Brenda Coley-Gaines, special projects program director for Planned Parenthood and coordinator of the conference. "If that is the case, evidently they the churches must be doing something right. Whatever that is, we want them to share that, not just within their church structure, but with the entire community."

According to Planned Parenthood, there were 4,539 births to teens out of a total of 38,591 births in the metropolitan area in 1983. The District of Columbia had the highest number of babies born to teen-agers (1,837), followed by Northern Virginia (1,315), Montgomery County (506), and Prince George's County (357).

The premise that churchgoing teens are less likely to have sex is based on studies dating back to the 1948 Kinsey Report, according to the Center for Population Options.

Planned Parenthood asked representatives of various denominations to join a Religious Advisory Committee to help develop and encourage sexuality education programs through religious institutions.

Established in November 1984, the eight-member committee helped Planned Parenthood plan the conference, which was attended by 35 clerics and lay leaders.

The half-day conference included workshops on the scope of teen-age pregnancy, starting a teen pregnancy prevention program, the value of values, and helping parents teach their children about sex.

"The church, like the family, is the primary sexuality educator for teen-agers," said Carmen Blackman-Williams, an education consultant and a member of a Baptist church who taught the values workshop.

"The school is a good place to get it sex education , but that to me is the last place to get it. You don't have the value systems taught at the schools that you have at the church or the home. And I think the ministers should be involved in this; so should lay people," Blackman-Williams said.

The conference keynote speaker was the Rev. J. Morgan Lewis, pastor of the Carron Baptist Church in Southwest Washington. "When I took on the pastorate of Carron," he said, "I encountered, the first week, several problems of teen-age pregnancy within my young congregation . . . . So I contacted Planned Parenthood to enlighten myself as to what I could do as a pastor, a person and a father to get to work on breaking the cycle of teen-age pregnancy within our congregation."

"I think one of the things I deem most important to changing this cycle of teen-age pregnancy is that churches, who speak each week to the largest black audience collectively of any . . . media in the city, is to reach out and say to our young people that there is virtue in living morally right . . . that there is virtue in waiting until marriage for sexual involvement."

Representing the Archdiocese Pastoral Center of Washington, Dominican Sister Rosetta Marie Brown, a counselor at All Saints High School in Northeast, said her school is looking into developing sex education information materials for its students, and has created a task force to study city problems, including teen-age pregnancy.