MAYBE I SHOULD have let her have the baby the teen-ager's mother said to me in a pique of pessimism as she sipped lukewarm coffee, her freckled hand trembling around the styrofoam cup. She was ending a nightlong nightmare at George Washington University Hospital where doctors were finishing an incomplete abortion the girl had received at a local clinic.

The regularity with which legal abortions occur in this country, despite the increasing hurdles the government is erecting, has made many outsiders like me feel the abortion table is a place for a casual encounter. I'd heard that many women have adopted an attitude bordering on the cavalier. My own philosophical position is firm. I feel an adult should have the freedom of choice.But as political arguments rage, with both sides seemingly fixed in their positions, no idea is putforward less often than the emotional trauma of the experience for some people. The abstractions crumple when it's someone with whom you are acquainted.

In Washington in 1977, aboutt 59 of every pregnancies uninterrupted by natural causes were ended by legal abortion. It's as if abortions are being used as a form of birth control for some. An abortion is at once both a simple and a complicated procedure, doctors say. So one family I know agreed to share its painful experience as a bell-wether, as a warning to proceed with care, to ask questions and to double-check.

The girl had wanted to keep the baby, a desire prompted either by rebelliousnes, a teen's abbreviated vision of the future, love for the father or whatever moral/cultural/ethical forces gathered within her. She wept and declared thatshe would "not murder my baby!"

The days after the revelation that this high school junior not only was pregnant but wished to give birth to the child were consumed bya long litany of entreaties that she not attempt the madness of becoming a child-mother.A family doctor's explanation that, legally, she was not yet carrying "life," as it was within the first trimester, reluctantly convinced her that having an abortion "would not make me a murder." But she was riddled with doubts; the marriage-shy teen-age father, a schoolboy himself, was ambivalent.

The air was heavy with hostility and tension as mother and daughter drove to the clinic in downtown Washington, which had been recommended by their family doctor. At $150, the abortion would be a $550 savings over a hospital stay since the family temporarily was without hospitalization insurance. Walking in, the mother tried to make the daughter understand that despite the family's wishes, the final decision remained hers.

When her name was called, the girl and her mother went to a counseling room and waited for 15 minutes, but nobody came. When it was time for the daughter to leave, the girl's back was rigid as steel as she disappeared into anotherroom; the mother's heart was lead as she departed the clinic.

When it was over, the mother returned for her daughter.

"Don't touch me, don't say anything to me," the girl hissed. "That doctor treated me like I was a piece of trash. He took off his gloves and threw them on the table when I told him he was hurting me," Then she aimed the final blow at her guilt-ridden mother: "Murderer!"

The daughter's moral steadily tumbledas she withdrew within herself. "They made mekill my baby," she confided to a friend a coupleof days later, a telling sign that although she had consented to the operation, she was a long way from solving the emotional turmoil that ensued.

Still, there were signs that she was beginning to pull out of her depression -- she went record shopping, her father provided money for her to buy clothes. Her mother tried to remain optimistic and cheerful despite the girl's sporadic outbursts. "Your life isn't over, it's just beginning," she'd say softly.

But the teen-ager was suffering from persistent physical pain and discomfort. Her screams awakened her parents at 2 a.m. and in a flash, the mother was down the hall at ther daughter's bedside. They called the clinic's emergency number. No answer. They didn't redial, but rather bundled the girl in blue jeans and a tan jacket and rushed her to Washington Hospital Center. That emergency room was a swirl of hurting humanity; a thin girl's shooting pains did not even rate a stretcher. After 45 minutes, they went to George Washington University Hospital where she was admitted and a decision made to operate.

At 7:30 a.m. the girl was rolled into the operating room, sullen and sick, and a mother who felt she had done what was best was worrying about the complications. "I told her she could have in the end refused . . ." she sighed, halfheartedly.

While doctor operated, the weary parents returned home to pick up a few items -- their daughter wanted a favorite stuffed animal among other things -- and the mother's mind was a merry-go-round whirled by weariness, guilt and her own ambivalence.

The telephone was ringing when at 6:30 a.m. she returned to her daughter, who stirred in a post-operative fog and reached for her Teddy Bear. It was the doctor, and his verdict was that some tissues -- "products of conception" -- from the incomplete abortion, as well as some infectious fluid.

It's one of the risks of abortion and did not necessarily imply negligence on the clinc's part the operating surgeon said. Despite the emotional turmoil this abortion engendered, I feel it wasa necessary one that underlines how important it is for people to have freedom to choose. But with nearly 30 percent of all pregnancies in America terminated by legal abortion, excluding miscarriages, in 1978, it also emphasizes that this procedure should not be taken lightly.

The family would seek professional help to clean up the emotional disarray, but first there was the hospital stay and the up-and-down task of getting well. And by the time the mother had amoment for that cup of coffee, which she'd commandeered off her daughter's breakfast tray, she'd reached an emotional low. She was wondering if "I should have let her have the baby and put it upfor adoption." But she know, too, how tough it is to get black babies adopted.

The daughter was hanging up the telephone after talking to her by friend as her mother entered the room from the hallway.

"Bob said he was going to happen," she said.

"How did he know?"

"he said he had a dream about it."

The woman could only shake her head. With such a long way to go to try to bring her family to wholeness again, there was time for onlya careless, yet poignant response.

"I wish," she sighed, "somebody wouldtell me about dreams."