WASHINGTON (AP) _ A baby born more than two months premature on a speeding jetliner was removed from a ventilator and taken off the critical list Sunday, his happy and relieved mother said.

''He's doing quite well,'' Theresa de Bara said in a telephone interview. ''He's responding quite well to the medication, basically his biggest problem is his lungs.''

The de Bara family boarded TWA flight 265 in New York on Wednesday as a family of three en route to a holiday trip to Disney World. Ninety minutes later the de Bara's left the plane in suburban Virginia an excited and anxious family of four - now counting Matthew Dulles, weighing in at 4 pounds, 6 ounces and was 17 inches long.

On the way, Mrs. de Bara, nearly seven months pregnant, went into labor and, with the help of a Long Island internist and two paramedics from Newburyport, Mass., Matthew Dulles de Bara was born 90 miles outside of Dulles International Airport in Chantilly, Va.

His parents decided Dulles should be a part of his name, given the role the airport played in his safe landing.

''It was just unadulterated terror giving birth in an airplane where you know they can't possibly be fully prepared for this type of thing,'' Mrs. de Bara said Sunday. ''With the help of God and the doctor and all those paramedics we just got through it. If I didn't believe in God at that time, which is not the case, I certainly would have called on him then.''

Santiago de Bara stayed behind at the hospital with his new son, while Mrs. de Bara returned home with the couple's 3-year-old daughter Amanda.

Leaving her new baby was ''just horrible,'' Mrs. de Bara said Sunday, ''but my husband is a lot more level-headed and could deal with the things that may have occurred with Matthew better than I could have. My daughter is better adjusted to dealing with me and my way of organizing things.''

Mrs. de Bara said she would be returning to her son's side Monday afternoon.

Dr. Steven H. Rachlin assisted Mrs. de Bara with the birth.

''Here I was on a vacation to relax, and then I was on an airplane being asked to deliver a baby. I was in an altered state,'' Rachlin told a reporter from The Washington Post on Friday. He said he had delivered only one baby before - 13 years ago.

He originally thought Mrs. de Bara was experiencing false labor pains. But the contractions became more frequent, and it appeared she was starting to hemorrhage.

''The pain just got worse,'' de Bara told the Post. ''She was holding onto my hand a sticking her (finger) nails into me. I felt helpless, I couldn't do anything. We had worked so hard for this baby. I didn't want it to end like this.''

The pain intensified as Flight 265 climbed to its cruising altitude of 30,000 feet.

As breakfast was being served about 30 minutes into the flight, the de Baras told a flight attendant they needed assistance.

Just at that time, Mrs. de Bara doubled over in pain as her contractions had started.

Flight attendant Connie Duquette hastily ordered passengers to clear the aisles and make space so Mrs. de Bara could lie down. Stretched across five seats, she screamed as the baby's head appeared.

Rachlin told Mrs. de Bara to take several deep breaths and push and the baby came out with the umbilical cord around his neck. The delivery was made 90 miles from Dulles.

But the child was not breathing. Jim and Jen Midgely, two paramedics from Newburyport, Mass., said they had delivered about a dozen infants and began to help.

Mrs. Midgely said her specialty was ''infant respiratory procedure,'' and she took a small straw and inserted it down the child's throat as Rachlin administered cardiopulmonary resuscitation.

The child finally began to breathe on its own after a few minutes. Duquette obtained a shoe lace from a male passenger to tie off the umbilical cord.

Meg Somerville, flight service manager on flight 265 said the crew undergoes annual training on in-flight deliveries, but added that Wednesday's episode was the first time she or any of her crew had put that training to use.

Somerville said her job was to provide a sort of play-by-play for the 150 other passengers. ''You can't expect all those people just to sit quietly without any information,'' she said.

''They were great through the whole thing,'' Somerville said. ''The only time they actually stood up was after the plane landed and I urged on an ovation to the doctors and the paramedics.''

Mrs. de Bara and her son were taken to Reston, Va., Hospital when the plane landed at Dulles.