THERE IS A PROBLEM," THE doctors say. But even before the words are out you've seen it in their eyes, sensed it in the way they peered at the baby as it struggled into life, bearing the mark of a moment when, in the twining dance of chromosomes that we call conception, something microscopic stuck or came undone. A problem. Two soft folds of tissue, groping toward one another in the darkness of the womb, failed to meet, somewhere in the three-dimensional complexities of the embryonic heart. Or the skein of nerves, spreading intricately from the bulb of the brain, left an unaccountable gap where no sensations flow, no muscles feel the impulse to move. And of all the things you might have wished for your child--wisdom or beauty or simple happiness--you are left forever after with one simple desire, a word that now embodies all your hope and longing: normal.
But these problems are a part of the human condition, exactly as prevalent now as they were when the United States began keeping detailed statistics in the 1960s, or for that matter in studies that go back to the 1890s: out of 100 babies, on average three are born with anomalies that will seriously affect their health. In one sense, this should be reassuring for expectant mothers who get nervous driving under electrical-power lines: while there is no doubt that drugs, radiation or industrial chemicals are capable of causing birth defects, these events are so rare as to be statistically negligible. (To the degree that birth defects are caused by environmental toxins, says Dr. Godfrey Oakley, head of the division of birth defects and developmental disabilities at the federal Centers for Disease Control, danger is more likely to be found in molds, vegetables or something else that has been with humanity for much longer than Alar or saccharin.) On the other hand, the great advances of the last 25 years in genetic science and embryology haven't done much to bring the rate of birth defects down, either. Surprisingly little research has been done on birth defects specifically, as distinct from human genetics; it was just last year that the CDC committed a modest $3 million to set up five centers to study the estimated 75 percent of birth defects whose causes remain a mystery.
Some problems are very well understood and can be prevented, although the prevention in some cases takes the form of an abortion. Abolishing fetal alcohol syndrome, which afflicts one baby in 1,000 with developmental problems, is as easy, and as difficult, as getting pregnant women to control their drinking. Four hundred micrograms daily of folio acid, taken before mad during pregnancy, cuts by two thirds the risk of having a baby with neural-tube defects such as spina bifida, a crippling failure of the spinal cord to close. Yet "the best evidence we have is that only one out of four women is actually following that advice," Oakley says. One problem: the vitamin must be taken in the very first weeks after conception; starting only after a pregnancy is confirmed may be too late. In the last four years, Oakley adds, there were more preventable birth defects resulting from folic-acid deficiency in the United States than in the infamous epidemic of thalidomide poisoning in Europe 40 years ago, when a drug prescribed to ease morning sickness turned out to cause babies to be born with flippers for arms and legs.
A more complicated case is that of cerebral palsy, a nerve disorder that can affect voluntary movements including walking, writing and speech. Many cases result from maternal infections during pregnancy, and when doctors began controlling these a generation ago they expected cerebral palsy to eventually disappear. Instead, the rate has increased by 20 percent in 20 years, to approximately two in 1,000 births. This is because doctors are now keeping alive many more very premature and low-weight babies, who are prone to brain damage from lack of oxygen at birth. Yet a recent study showed a virtual elimination of cerebral palsy in at-risk babies whose mothers received the drug magnesium sulfate, which appears to protect the brain against the toxic effects of oxygen deprivation. Thus the partial conquest of this crippling condition may yet be at hand, allowing for the fact that it can also be caused by lead poisoning, head injuries, encephalitis and probably several other things that we don't even know about yet.
But cerebral palsy is far from the worst problem a baby can be born with. The very worst things that can go wrong with an embryo are never encountered, because they are lethal long before birth, in some cases before the woman even knows she has conceived. By definition, a fetus born alive is a survivor, although sometimes the parents have no choice but to start mourning there and then. Babies born without brains (anencephaly) or with extra copies of chromosomes (trisomy) rarely live for more than a few days or weeks, except in some special cases, of which the best known is Down syndrome.
These conditions are rare, however. The most common lethal defects, although still accounting for only a fraction of 1 percent of all births, are malformations of the heart. Fortunately, these are problems that surgeons have learned to treat (chart). Few conditions are more devastating than hypoplastic left-heart syndrome, in which the main pumping chamber fails to develop, and as recently as 15 years ago it was invariably fatal. But a threestage operation developed by Dr. William I. Norwood, in which the right ventricle is made to do the job of its underdeveloped partner, now keeps some of these children alive, at least until they can receive a transplant. Transposition of the aorta and pulmonary artery, which results in the heart's recirculating unoxygenated blood out to the body, used to be fatal about 90 percent of the time, but now has a 90 percent survival rate after surgery. Advances such as these, plus better neonatal intensive care generally, have contributed to what Dr. Richard B. Johnston, medical director of the March of Dimes, says is a 50 percent drop in deaths from birth defects since the 1960s.
Down syndrome in theory is completely preventable, in the sense that there is a reliable test for the extra chromosome known to be its cause, after which the pregnancy can be terminated. Of course, that's not a solution to everyone's taste, and around 10 percent of women who know their babies will be born with Down syndrome go on to have them anyway, says Dr. Barbara K. Burton, director of the genetics center at Columbia Michael Reese Hospital in Chicago. But even though the other 90 percent do have abortions, the number of Down syndrome babies born each year is not declining, because more women are becoming pregnant later in life, when the chance of having a Down syndrome child rises dramatically. Burton estimates that only 6 to 8 percent of pregnant mothers get the tests--amniocentesis or chorionic villus sampling--that can detect the extra chromosome. Some of them may be put off by the slight risk of miscarriage, but a new test that may be available as early as next year promises to end that danger, according to Dr. Allen Horwitz of the University of Illinois College of Medicine. The procedure involves locating the infinitesimal quantity of fetal cells that cross the placenta into the mother's bloodstream, so only a sample of her blood would be required. "It's a way of finding samples of genes or chromosomes of the fetus without invading the uterus," says Horwitz.
And what of the mothers who have their babies anyway? A generation ago they would have been told that their child might never learn to speak, was certainly ineducable and probably should be sent to an institution-where, says David Patterson, president of the Eleanor Roosevelt Institute (which promotes genetic research), life expectancy was around 9 years. Unnumbered thousands of children perished in neglect that way, before an astounding paradigm shift that began in the 1970s, with parents who insisted on taking their Down syndrome babies home with them. With adequate care, it turned out, Down syndrome children didn't have to die before the age of 10; life expectancy now is 58 and rising, according to Patterson. With someone willing to teach them, most could learn to read, and some, says Lori Atkins of the National Down Syndrome Society, even have driver's licenses. It is possible, in short, for a Down syndrome child to hold a job and live at least a version of the sort of life that every parent dreams of from the moment he or she hears the fateful news that a child has "a problem." A normal life.
When Things Go Wrong: Birth Defects
Birth defects can arise from inherited genetic abnormalities as is the case with sickle cell anemia, from viruses such as those responsible for rubella, from poor prenatal care-or from reasons so mysterious they can only be labeled fate:
Most common birth defects* Occurrence Congenital heart defects 1/110 Narrow stomach/intestine junction 1/250 Congenital hip dislocation 1/400 Sickle cell anemia 1/400 [t] Cerebral palsy 1/500 Cleft lip/cleft palate 1/730 Clubfoot 1/735 Down syndrome 1/900 Fetal alcohol syndrome 1/1,000 Hearing impairment 1/1,000 Other birth defects Occurrence Spina bifida 1/2,000 Cystic fibrosis 1/2,000** Fragile X syndrome 1/2,000 [tt] Congenital HIV infection 1/2,400 Missing/underdeveloped limbs 1/2,500 Duchenne muscular dystrophy 1/3,500*** Anencephaly 1/8,000 [ttt] Congenital rubella syndrome 1/100,000 *LIVE BIRTHS, IN THE U.S. [t] BLACK BABIES. ** WHITE BABIES. [tt]MOSTLY BOYS. ***BOYS. [ttt]OCCURS IN 1/2,000 TOTAL PREGNANCIES, BUT BABIES ARE OFTEN STILLBORN OR ABORTED. SOURCE: THE MARCH OF DIMES, CENTERS FOR DISEASE CONTROL