ST. PAUL, Minn. (AP) _ Medical records do not support a woman's claim that the Copper-7 intrauterine device caused her infertility, an attorney for the IUD's manufacturer told a federal jury Tuesday.

''When the question is a medical one, we must look to the medical records for the answer,'' Paul Strain, an attorne for G.D. Searle & Co., said in opening arguments.

A jury of five women and three men is hearing the civil suit against Searle by Esther Kociemba, 29, and her husband, William, of Elk River.

Michael Ciresi, an attorney for the Kociembas, said in his opening arguments that Searle displyed ''corporate irresponsibility'' by withholding knowledge that its Copper-7 IUD had the potential to cause infertility.

''It's a story of a company closing the door on the God-given right of a woman to bear children,'' Ciresi said.

But Strain said attorneys for Mrs. Kociemba would be introducing evidence not central to the issues involved in the case.

''This is a case about whether they (the plaintiffs) have met the burden of proving that the Copper-7 caused the infertility of Mrs. Kociemba,'' Strain said.

The Kociembas are asking for an unspecified amount in compensatory and punitive damages for injuries, including infertility, that Mrs. Kociemba allegedly suffered as a result of using a Copper-7 IUD for about 1 1/2 years in 1977 and 1978.

Ciresi called as his first witness a doctor who testified that inserting an IUD can introduce bacteria into the normally sterile uterus.

Dr. Richard L. Sweet, chief of the department of obstetrics and gynecology at San Francisco General Hospital and co-author of the book ''Infectious Disease of the Female Genital Tract,'' also said an IUD can ulcerate the uterine lining and that the ulcerated lining is not expelled completely during a woman's menstrual period, as Strain had indicated in his opening argument.

The fallopian tubes, which carry eggs from the ovaries to the uterus, are probably the part of the upper reproductive tract most susceptible to infection caused by invading bacteria, he added.

Mrs. Kociemba claims that the Copper-7 infected her uterus, resulting in pelvic inflammatory disease and, ultimately, tubal infertility.

Ciresi's law firm, Robins, Zelle, Larson & Kaplan, represented plaintiffs in many of cases involving A.H. Robins Co.'s Dalkon Shield, which was eventually withdrawn from the market. The firm is representing more than 30 women in Copper-7 lawsuits against Searle.

While the Kociemba case is the 18th involving the Copper-7 nationwide to go to trial, it is the first being tried by Robins, Zelle, which has said it will introduce internal Searle documents never before presented.

The firm has said evidence introduced in the Kociemba trial is expected to set a foundation for lawsuits to come.