A major civil suit against G.D. Searle & Co., maker of the Copper 7 intrauterine device, ended in a mistrial today after jurors declared themselves deadlocked after three days of emotion-charged deliberations.

The lawsuit in U.S. District Court was brought by 17 women from around the United States and Canada who contend that the controversial Copper 7, the most widely used IUD in the country, caused them injuries that left them unable to bear children.

Shortly after 5 p.m., foreman Roy R. Reed told Judge Joseph Young that the jury of four women and nine men were was unable to reach a verdict.

Two of the women jurors were in tears when they left the court, and Reed said afterward that emotions had run high in the jury room, with the women generally "more partial" toward the plaintiffs than the male jurors.

Outside the courtroom, a female juror tearfully hugged plaintiffs' attorney Patricia Jo Stone and said, "Keep pressing on with it because this is something women need to know about. It can't be hidden any longer."

Both sides said they intend to retry the case, probably early next year. None of the plaintiffs was in court when the jury returned today.

Reed and other jurors said they were unable to agree on any of the issues presented in the three-week trial, which included often contradictory testimony from medical experts.

Most of the jurors were white-collar professionals who appeared to take a keen interest in testimony throughout the trial. Many took copious notes.

After questioning the foreman and learning that jurors believed there was no point in further deliberations, Young told the panel, "You've been most conscientious . . . as much so as any jury I've ever seen."

The Copper 7, which has been on the market since 1974, is being used by about 1 million women in the United States, according to Searle. The plaintiffs in the suit claimed that the device can perforate the uterus, cause ectopic pregnancy, in which fertilization occurs in the Fallopian tube, and pelvic inflammatory disease, a serious infection that can cause sterility through scarring of the uterus and Fallopian tubes.

Jurors were asked to determine whether the Copper 7 causes those conditions and, if so, whether Searle could be held liable for marketing a defective product or failing to warn doctors of its potential hazards.

Searle maintains that many of the health problems suffered by the plaintiffs were due to other causes, including sexually transmitted diseases. Had the jury found Searle liable, the trial would have resumed for a second phase in which each of the plaintiffs would have had to prove her injuries were a direct result of use of the Copper 7.

Several hundred Copper 7 lawsuits are pending against Searle, and several hundred others have already been settled out of court or dismissed. This case has drawn national attention because of the number of plaintiffs involved and because a number of internal company documents damaging to the Illinois-based company were expected to be introduced as evidence.

The judge, however, did not allow the documents, which relate to the way Searle conducted animal tests of the Copper 7, to be introduced.