A former prominent Fairfax County doctor used his own sperm to impregnate women who came to him for treatment of fertility problems, fathering at least seven children, according to a federal indictment returned yesterday in Alexandria.

Cecil B. Jacobson, a former George Washington University geneticist who owned the Reproductive Genetics Center Ltd., of Vienna, also was accused in the indictment of repeatedly injecting women who paid up to $5,000 for fertility treatments with a drug that would falsely indicate in tests that they were pregnant.

Jacobson, who agreed to stop practicing medicine three years ago after an investigation of the injection treatments, allegedly told his patients that when the pregnancy failed to develop, the baby had miscarried or been "reabsorbed" into the mother's tissues.

U.S. Attorney Richard Cullen, whose office is prosecuting the case, described Jacobson's alleged scheme as the cruelest possible form of fraud.

"You've got people going to a doctor for the most basic and sacred of events, the most private of events, and sometimes at the most vulnerable times of their lives," Cullen said. "They are seeking advice in what could be the most important decision of their lives, and that trust is violated."

"These people," he added, "have suffered immeasurable harm."

Prosecutors refused to explain yesterday how the seven couples whose children allegedly were fathered using Jacobson's sperm learned of the situation, saying that those details could jeopardize the couples' privacy. Sources familiar with the case said that at the time of the complaints about the injection treatments three years ago, there had been no complaints involving Jacobson's sperm donor program.

The couples are identified in the indictment by pseudonymns and have verified Jacobson as the father of the children through medical testing, according to the indictment.

James R. Tate, Jacobson's attorney, described allegations that his client had impregnated his own patients as a non-issue. "They had children and now they're complaining about the source of the sperm," Tate said. "Frankly, I think it's a red herring to try to get people not to focus on the merits of what Cecil was trying to do."

Tate also said that during the period covered in the indictment there was a heightened awareness of AIDS and that if his client did use his own sperm, he did it "knowing that his semen is clean and good."

Richard R. Boone, an attorney who represented a woman who sued Jacobson over the injections, said he heard several years ago that a former employee of the doctor told the media that Jacobson had used his own semen in the insemination procedures.

"The explanation to the patient would be given that he liked to use fresh sperm because the procedure had a better possibility of success," Boone said. "He would say the sperm donor is waiting in the next room, and he would go obtain the sample. He would disappear and come back within a few minutes with a fresh dose of semen."

The indictment affirms Boone's version of events, saying that shortly after a patient arrived for the procedure, Jacobson "went into the office bathroom and generated an ejaculate, such ejaculate then being used to fraudulently inseminate certain patients."

Jacobson, 55, now a resident of Provo, Utah, was charged in the indictment with 53 felonies, including several counts each of mail fraud, wire fraud and travel fraud, for using the Postal Service and phones to carry out his allegedly fraudulent fertility practice.

He also was charged with perjury for allegedly lying to the Federal Trade Commission, which obtained an injunction against his practice three years ago. In a consent decree with the FTC, Jacobson was required to set up a $250,000 fund to reimburse some patients who had been deceived by him.

The doctor also was the subject of several civil suits and a 1989 ruling by the Virginia Board of Medicine that effectively prevented him from practicing medicine again.

Jacobson, who had a distinguished reputation in obstetrics and gynecology, performed the first amniocentesis, a procedure that can detect abnormalities in fetuses, in the United States.

Deborah Gregory, a Fairfax Hospital employee who sued Jacobson several years ago, said she went to Jacobson over a period of years and received "many, many, many, many injections and was told on three occasions that there were supposed pregnancies."

Gregory, now 40 and still without a child, said her experience with Jacobson cost valuable time that she and her husband will never recover in their efforts to conceive children.

"We lost a number of years, important years," Gregory said. "But I haven't given up hope. I'm an eternal optimist."

Complaints against Jacobson were first aired in 1988 on WRC-TV (Channel 4) and were followed later by a segment on "60 Minutes."

According to the indictment, Jacobson ran his clinic from 1976 until 1988.

During office visits, the doctor described himself as "the babymaker" and told one patient, "God doesn't give you babies -- I do," according to the indictment.

Jacobson administered frequent and large doses of the hormone known as human chorionic gonadotropin (HCG), although women receiving fertility treatment usually get a one-time dose at the time of ovulation, court documents said. Pregnancy tests reacting to the hormone indicated the woman was pregnant when she was not.

Jacobson conducted frequent ultrasound examinations of the women, referring to supposed fetuses as "junior" and telling the patients that the fetus was growing properly, according to the indictment.

When a period of weeks had passed, Jacobson told patients the baby was "gone" or "your baby is dead," explaining that they had suffered a miscarriage. According to the indictment, Jacobson discouraged patients from seeing gynecologists, saying there was no need because the baby's tissues would be reabsorbed quickly into the patient's system.