Some leading American scientists warned yesterday that science cannot be sure yet the test-tube babies will be physically and mentally normal human beings.

Some went on to call for far more research in the laboratory and in animals before any test-tube embryos are implanted in human mothers, as in the procedure that produced was the child born in England Tuesday.

Federal health officials said they agree. They said they will continue a 3-year-old moratorium on any studies involving even the first step of combining human ova and sperm until a new National Ethics Advisory Board - a board disposed to go slowly - gives its approval.

Nonetheless, it was learned yesterday, over the past two years scientists at four major medical centers - Harvard, Cornell, Vanderbilt and the University of Pennsylvania - have told federal officials they want to resume or start such experiments.

They argue that forbidding such work, at least in the test tube, could cost society dearly in continued ignorance of the human fertilization process. Better understanding, they said, might lead to new ways of contraception acceptable to all religions, as well as simpler ways to cure infertility and ways to prevent genetic diseases.

These were a few of the developments yesterday in the wake of the birth of a baby girl to John and Lesley Brown in England. Mrs. Brown had successfully carried the embryo to term after an egg, fertilized by her husband's sperm in a laboratory vessel was reimplanted in her womb.

The first great pressure in this country, it became clear, will fall on the 12 persons so far named to a planned 14-member Ethics Advisory Board of the Department of Health, Education and Welfare.

"This is the first project we're going to undertake," said a key member, the Rev. Richard McCormick, professor of biological ethics at Georgetown University and a Catholic widely recognized as a leading thinker in the difficult field of applying science's new knowledge of life and death.

"Our staff will begin to gather background information in August," Father McCormick said. "I feel fairly clear there will be a marked increase to requests for this procedure from couples whose marriage is sterile. There should also be a marked increase in requests for federal funds for research."

Father McCormick said "I have real serious questions and problems that lead me to take a negative position" on this issue "at this time." He said that his still a "tentative" position, although a Vatican spokesman in Rome said yesterday that the Catholic Church considers any artificial human insemination illicit.

Although he is a noted Catholic theologian, McCormick does not always take orthodox church positions. But he cited such moral problems as the destruction of test-tube embryos judged unfit to survive.

"We may have doubts" about whether that mere speck-sized clump of cells is or is not "fully a human being," McCormick said. "And when there is doubt, I want to go very slowly and cautiously."

HEW's ethics board's vice chairman - Dr. David Hamburg, head of the institute of medicine, within the National Academy of Sciences - likewise said, "I think we're going to be very cautious about this in this country. I think we're going to be very slowly."

Board member Sissela Bok, medical ethicist and wife of Dr. Derek Bok, Harvard president, said, "I don't think that because it happens in England, it can automatically happen in the United States." She doubted that the British birth will make it easier for American researchers to get federal funds.

Human fertility researchers at Vanderbilt University in Nashville and the University of Pennsylvania in Philadelphia lost their federal support in 1975.

HEW decreed then that "no application or proposal involving human invitro fertilization may be funded" until an HEW Ethics Advisory Board "rendered advice" on its ethics. In-vitro, or in-glass, means under laboratory conditions.

HEW Secretary Joseph A. Califano Jr. did not start appointing people to the ethics board until last fall, and so far it has had just two meetings.

Dr. Pierre Soupart of Vanderbilt said that he is eager to start tests on whether or not there is any increased risk of genetic abnormalities when human ova or egg cells are joined with male sperm cells in a glass container instead of the body.

At Pennsylvania, Drs. Luigi Mastroianni and Benjamin Brackett said that there should be much more laboratory work and trials "in many more animals" to make sure the test-tube fertilization will not cause future mental deficiencies or physical deformations.

Mastroianni is head of obstetrics and gynecology at the University of Pennsylvania Hospital. In the reports the British doctors have made so far - reports of previous unsuccessful attempts at such births - they have said they used hormones to prepare the womb and help maintain the pregnancies.

These hormones are agents "our Food and Drug Administration would never allow," Mastroianni said, "because of the risk of producing congenital abnormalities," or problems in the test-tube children's future off-spring.

"It's one thing to have a cookbook trial-and-error method and maybe have a success and maybe not," Masstroianni added. "What we really need is basic research in fertility. I'm just appalled at the lack of information on it."

His group is doing some work with human ova and sperm but with private funds, he reported.

Until there are ample federal funds, Brackett said, there is little hope of extending the animal work that has so far seen successful test-tube fertilization and apparently normal births in at least three species: rats, mice and rabbits.

He said that he himself has performed around "a few hundred" implants into rabbits, with about 100 off-spring resulting. Other scientists have produced successful offspring in "probably a couple of hundred" mice and "something under 100 rats," he reported.

In all these, he said, "I don't think there is any substantial evidence for any abnormalties attributed to the procedure." The problem, he said, is that the numbers of animals involved is too small for a valid analysts.

"So the normality of the offspring is still somewhat in question," he concluded."We really don't know the effect of the mechanical and chemical manipulation of an egg prior to fertilization."

In San Antonio, Dr. Carl Pauerstein of the University of Texas said, "in our country we're concerned about the unknown possibilities . . . We're concerned that we might induce some congenital effects."

Patrick Steptoe, the Brown baby's chief doctor, has said in the past, "I'm not a wizard or a Frankenstein tampering with nature. All I want to do is to help women whose child-bearing mechanism is slightly faulty."

"What I worry about," said a scientist here who asked not to be named, "is the effect on all scientific progress if this or another experiment like it goes wrong. Has society really given us enough of a go-ahead?"