The Journal of the American Medical Association is warning doctors and parents that "elective" or medically induced deliveries, which are growing in popularity in many parts of the country, may produce babies with serious physical problems.

An article and an editorial in the new issue of the weekly journal out today say doctors should avoid speeding up delivery - sometimes by drugs, sometimes by cesarean operation - unless there are good medical reasons.

The author of the editorial, Dr. Howard McQuarter of Salt Lake City, said cesarean operations have doubled in the United States in the last 10 years. He said as many as four babies in 100 in newborn intensive-care nurseries in "widely diversified" parts of the country are admitted after medically unneeded induced deliveries.

Delivery is sometimes induced for the mother's convenience, he said, sometimes for the doctor's, sometimes at the urging of a hospital that wants to concentrate births to cut costs.

But the cost of care for one possible result - fetal lung disease - is $2,678, on the average, say Dr. M. Jeffrey Maisels and co-workers at Pennsylvania State University Hershey, Pa., Medical Center. They say 6,000 of the 40,000 such cases every year in the United States may be preventable by full-term delivery, at a saving of $16 million for initial care alone, not considering any later physical problems.

"What may happen is that a doctor is going out of town and the mother wants only him to deliver her baby," said McQuarrie. "Or she may be very busy and wants to get the last very uncomfortable part of pregnancy over with. I tell such mothrs, "Why take a chance?"

Of 1,020 consecutive sick infants admitted to the Pennsylvania center, according births required by "no medical condition of the mother or fetus." Eighteen of the 38 had fetal lung disease "clearly related to premature delivery." One died.

The price of medically unneeded deliveries may thus be medically caused lung and breathing difficulties, failure of normal growth and development and other mental and physical deficiencies later, said McQuarrie.

He said the new studies of the problem at both the Hershey and Akron, Ohio, newborn intensive-care centers are among many indications that it is widespread. Babies are delivered at many hospitals, but only the sickest are moved to regional intensive-care units, so these units may act as barometers of any problems.

This problem may not be universal, however. Dr. Allan Weingold, chief of onstetrics at George Washington University here, said that are few induced deliveries "in our system" - GW and cooperating hospitals. In every such case, he said, there must be firm evidence, of fetal maturity (the baby's rediness to be born), confirmed by multiple tests.

Both he and Dr. Robert Parrott, director of Children's Hospital, said they know of no rash illness caused by early deliveries in this area. But Parott added that the statistics are not thorough, " and there are a lot of cesareans here."

Nationally, said McQuarrie, he thinks 10 to 15 per cent of all babies are delivered by cesarean today " and as many as 25 per cent in some places," though usually there are more drug-induced early deliveries than cesareans. "We need a good study of this problem every places," though usually there are more drug-induced early deliveries than cesareans. ="We need a good study of this problem every place, ns. "We need a good study of this problem every place," he said.

Sometimes, he pointed out, there are many good reason for induced deliveries even when mother and baby seem healthy. For example, parents may live too far from a hospital to be sure of getting there in time. But in such cases, tests should establish that the baby is fully ready, Weingold said.