The decision was, as they say, a tough one. When I was feeling academic, I called it the second child dilemma: Should we, could we, tolerate the lifestyle changes that having another baby would bring?

We are not exactly what you'd call a "trendy" couple, but for several years we've been right in style: a two-career family, with our first child born as I approached 31.

For the past four years, my husband and I have delighted in the advantages of having an only child. The "hard" part is over, day care arrangements are well established, and life has settled into a series of manageable routines. Andy goes on trips, to movies and to museums with us -- and has culinary sensibilities sufficiently well developed to prefer dining at what he calls "two-fork" restaurants.

But time was pressing us to make decision. Knowing full well that increasing numbers of children are born to women in their mid- and late 30s, we also knew that children of such women have a greater likelihood bo being born with sever abnormalities.

So we went back and forth on the second child; when one said "yes" the other said "no," with a daily dose of "maybes" thrown in to stir things up.

In the end, however, family won out. My own family has proven to be an important comfort to me; I very much wanted Andy to have that same support. (Of course, we knew there would be no guarantees. Most likely, the siblings would hate each other for the first 10 years.)

Conception was easy. We did it on a "girl" day -- outlined in one of the latest "how-to" books -- and not long afterward surprised everyone with the announcement that I was pregant.

"I think I'll have an amniocentesis," I said to my doctor at the first visit.

"What for?" he countered. "You're only 34. It's not until you get up to 38 or 39 that you really have to worry." Out came the statistics: one chance in about 400 of having a Down's syndrome baby at my age.

"I think I'll have it anyway," I said.

"I'm not going to tell you not to, but if you were my wife, I'd say don't bother."

I'm not your wife."

Amniocentesis, or analysis of the amniotic fluid surrounding the fetus in the uterus, is a procedure that can determine if the baby will be afflicted with any of several severe genetic disorders. There is a rish -- albeit small -- from the procedure itself. But to us, the advantages far outweighed the risks.

It was difficult enough to make the decision to have a second child. Given that an amniocentesis could rule out certain deforities-- we opted for the procedure.

We did have to consider the question of money. Fees for an amniocentesis are high, ranging from $500 to $700, and we wanted to establish whether our health insurance would cover it. It did, because I would be 35 at the time of the birth.

Now it was just a matter of time. Amniocentesis procedures for genetic defects -- such as Down's syndrome (mongolism), anencephaly, spina bifida and so on -- are best performed from 16 to 18 weeks into pregnancy. There are generally tow steps: First, a sonogram, or sound picture, is made to determine fetal size and position, and, second, fluid is drawn from the amniotic sac through a needle inserted into the abdomen. It is with that fluid that laboratory tests for chromosomal damage are done.

The sonogram was great fun. (In ultrasound, a machine sends out high-frequency sound waves that are inaudible to the human ear. In this case, sound was transmitted through the body to my uterus, reflecting back on a screen to create a picture of the uterus, placenta and fetus.)

As I lay on the table, the radiologist rubbed what felt like a pencil across my belly. And on the screen I saw a duck. Or, at least, a tadpole. It had a clearly defined head, with something that vaguely resembled a body attached to it, and it was swimming merrily in a sea of dots.

"A nice, healthy baby," the doctor said as he snapped some pictures. He gave me two Polaroids to take home, and said that he would do some measuring, to calculate fetal size. "Call in two days," he said, "and you'll know how far along you are." The pictures were my prized possession. I showed my duck to everyone who would look.

It probably had nothing to do with the eventual outcome, but those calculations gave me what I felt was my firs clue. The fetus, the radiologist said, was at least a week behind schedule. Instead of being 16 weeks "large" it was 15. That meant another three-week wait before the actual amniocentesis could be performed.

I am not by nature a suspicious person, but something lurking in the deep, dark recesses of my brain told me not to make any plans until I had the results of this test. I had no reason to suspect anything -- there is no history of genetic deformity in either my or my husband's family, and we had already had Tay-Sachs disease ruled out when I was pregnant the first time. But I was going through a process that could identify severe and gross abnormalities, and as long as I was subjecting myself to all this poking and prodding, I determined not to make any major "life" decisions.

That meant I'd decide what to do about taking leave from my job -- later. "Don't bring back the bassinette," I told my brother. And of course we didn't have to think about names. One of the more pleasant byproducts of amniocentesis is that we would know the baby's sex. Soon our choices could be narrowed considerably.

Finally, the day of the actual amniocentesis arrived, and I was surprised at how tense and anxious I was. The whole thing, doctor's spiel included, took about 10 minutes. It was relatively painless, although afterward I did have some discomfort. A glass of wine was prescribed to alleviate that -- a genuine treat because I had been told in no uncertain terms to abstain from alcohol for the entire pregnancy.Now all that was left was to wait for test results.

The call came in two weeks -- two weeks earlier than I expected "Trisomy 21 -- Down's sydrome," the doctor said, and we immediately had what I later realized was a "shock" reaction.

Stunned and stupefied, I was flooded with an overwhelming sense of relief -- relief that I had had the amniocentesis, relief that I had found out before carrying the baby to term, relief that we could do something about it. We called everyone we know -- talking, talking, talking -- as if, magically, that would eradicate the news we had just received. And how we intellectualized, telling ourselves that we were lucky, that we had been spared a great tragedy, that we were dealing with this as well informed, thinking persons do. The hysteria came later.

That night, what had been an inactive baby did cartwheels inside me. Andy coughed all night and I was sure he was going to die. I cried until dawn, unable to erase from my mind the picture given to my by the radiologist. Next moring I destroyed those Polaroid snapshots.

How could it have happened to me" I was only 34 when I conceived, 35 the day before I had the amniocentesis. (How we fix on numbers at times like this! As if there could be a rigid dividing line between riskless and high-rish pregnancies.) If only I had just lost the baby, without knowing what was wrong. If only, if only . . .

Numb and exhausted, I went to the doctor's office the next morning. I was to enter the hospital at the beginning of the week, when he would perform a therapeutic abortion. By this time I was 20 weeks into the pregnancy, so steps would have to be taken to ensure that the fetus would not be alive when finally expelled.

A substance (prostaglandin) would be injected to induce labor -- a process that might take up to 24 hours to complete.

In the hospital the first night, I cried myself to sleep. Next morning, on the table, I cried, "Am I hurting you?" the doctor asked. "Not physically," I said, as the tears spilled out from my eyes, and from those of the doctor and his assistants. Back in my room, I cried to the nurses, to my husband, to my mother, to whomever would listen.

Finally, 15 hours later, the fetus was no longer inside me. I was even robbed of a chance to expel it by myself; she (it was a girl -- I had to ask) was lying transverse, and so the doctor had to go in and take her out. My husband looked at the fetus (how could he?), and it was over.

It is now some months later and I am getting better. I know that we were all spared a great and much more enduring tragedy -- that which engulfs a family into which a deformed or retarded child is born. We have lived full lives -- but what about those endless years that Andy would face, forever living in the shadow of a retarded sibling? And what could life possibly have given to the child herself? If her mental development were sufficient to permit some degree of intellectual awareness, how would it feel to face life from behind those barriers of meager comprehension and infantile communication" (I later found out that it was not Down's syndrome but a different trisomy, that is , different damage to a different chromosome -- far more severe, in fact.)

I am getting better, but I am still not over it. I suppose I never will be. There will always by pain, grief and private tears triggered by almost insignificant events: the sight of a pregnant woman who looks older than I, or a chance encounter with a person who suffers from Down's.

And on occasion I get a "pang" for Andy, who will never have that sibling.

(Oh, we could try again, I know, but the thought horrifies me.)

Yet, really I know I have improved because now I can say to myself: How lucky that it was not my first pregnancy, that I have one lovely child and a family that has given my an incredible dose of emotional support. How lucky that I live at a time when amniocentisis is possible. How lucky that I was able to terminate the pregnance, that I did not have to fight, beg or borrow for the abortion, which was far more expensive than an obortion performed early in pregnancy.

But the grim facts are that others are not so lucky. How many pregnant women even know of the options available to them (for genetic counseling, amniocentesis, Tay-Sachs screening, etc.)? How many can afford the procedures? How many are military wives or Medicaid recipients, for whom there is no federal funding for abortion -- even in cases of known fetal deformities?

I remember reading about the tragedy endured by a woman named Donna Edwards, who -- because her husband was in the military -- was forced to carry her pregnancy to term even though it had been established that the baby would be anencephalic, that it would have no skull or brain and could not possible survive. The government, you see, does not fund abortions; the Edwards family could not afford a "civilian" abortion because abortions performed later in pregnancy are complicated and expensive.

What I learned is how niave I was. Before I has the amniocentesis and subsequent abortion, I though that if something went wrong, we would just take care of it. Intellectually, it all sounded so simple. But those decisions that seem easy when you read of others making them have a way of enveloping you with ponderous, deadly difficulty. I know I was completely unprepared for the emotional upheaval, the grief, the pain. But for one thing I will be enternally grateful: At least I had the choice.