Over nearly four decades since Prozac was approved for the treatment of depression, waves of concern about the effects of antidepressants during pregnancy have resulted in a practical consensus: Though use of the drugs may be associated with a slight rise in the odds of birth defects, the risk of leaving a mother’s depression untreated is often greater.

But a high-level shift is taking place within the Department of Health and Human Services under Secretary Robert F. Kennedy Jr., who has made reducing the prescription of psychotropic drugs a policy priority.

Among the select group of experts convened by the Food and Drug Administration on Monday to discuss the safety of antidepressants during pregnancy, around half said that women should receive a more clear and forceful warning about potential risks to the fetus.

Andrew Nixon, an H.H.S. spokesman, said the agency would not comment on whether there were plans to require a so-called black box warning about the use of selective serotonin reuptake inhibitors, or S.S.R.I.s, in pregnancy.

In his introductory remarks, F.D.A. commissioner Dr. Marty Makary said that “some women are not aware” of the risks of taking antidepressants in pregnancy, suggesting openness to the idea. Around 5 percent of pregnant American women take antidepressants, he said.

“Serotonin might play a crucial role in the development of organs of a baby in utero,” Dr. Makary said.

He added that S.S.R.I.s have been “implicated in different studies to be involved in postpartum hemorrhage, pulmonary hypertension and cognitive downstream effects in the baby, as well as cardiac birth defects.”

After the event ended, some experts who watched the panel described it as unbalanced, favoring prominent critics of antidepressants over those who treat severely ill patients.

“I am far more concerned about the risks of untreated illness than I am about the risk of medication,” said Dr. Nancy Byatt, a perinatal psychiatrist at the UMass Chan Medical School.

Studies conducted over many years, on hundreds of thousands of women, have concluded that antidepressants do not cause major harm to the developing fetus, she said.

Members of the panel were blunt, and, at times, alarming in their comments.

“The public needs better information, and the F.D.A. must strengthen the warnings,” said Dr. Adam Urato, chief of maternal and fetal medicine at the MetroWest Medical Center in Framingham, Mass.

“Never before in human history have we chemically altered developing babies like this, especially the developing fetal brain, and this is happening without any real public warning, and that must end,” he said.

Another panelist, Dr. Josef Witt-Doerring, the founder of a “tapering clinic” that helps patients quit psychiatric medications, said that many women taking antidepressants came to him when they wished to start families. He tells them about risks to the fetus, like congenital heart malformations and neurodevelopmental problems.

“They’ve never heard of these things, and they feel incredibly betrayed,” he said. “You know, ‘Why didn’t anyone bring this up with me when I got started on this medication?’”

Among the other panelists invited by the F.D.A. were two British psychiatrists with long records of criticizing the use of psychotropic medication.

Dr. Joanna Moncrieff is the author of “The Bitterest Pills: The Troubling Story of Antipsychotic Drugs” and “Chemically Imbalanced: The Making of and Unmaking of the Serotonin Myth.” Dr. David Healy has served as an expert witness in homicide and suicide trials involving psychotropic drugs.

The two-hour panel, which was livestreamed over the F.D.A.’s social media channels, signals a pivot on the question and is likely to add fuel to a grassroots movement that questions the rising use of psychiatric medication.

Only one panelist, Dr. Kay Roussos-Ross, an expert in postpartum health at the University of Florida, made the case that antidepressants could be a critical tool in treating pregnant women who may use substances or forego prenatal care if they relapse.

“Not every single woman will need an antidepressant, but for those that do, this is life-changing, and this is lifesaving,” she said.

Dr. Byatt said a warning from the F.D.A. was not likely to alter the practices of specialists in the field, but it might make women fearful about taking antidepressants.

“So many women I see feel guilty about taking medications,” said Dr. Byatt, a member of the Council on Women’s Mental Health, which is part of the American Psychiatric Association.

“They think they should ignore their needs for their babies. And I think it could make their decisions a lot harder, and the conversations we’re having with them a lot harder, because it could cause unnecessary alarm.”

Christina Caron contributed reporting.