Pregnancy After 35 Has Risks, but Amniocentesis Can Alert Mothers in Time, Says An Expert
01/14/1980 at 01:00 AM EST
As more women postpone childbearing until their mid-30s, often for career reasons, a new element of risk is added: Mothers of 35 and older give birth to nearly one-fourth of all babies with mongolism, although such women constitute only about five percent of all mothers. Risk of other genetic disorders also increases. In the past 15 years, however, a prenatal diagnostic technique has been developed which can alert mothers and physicians to chromosomal abnormalities in the fetus 15 weeks after conception. It is called amniocentesis. A pioneer in the field is Dr. Aubrey Milunsky, 43, assistant professor of pediatrics at Harvard Medical School and medical geneticist at Massachusetts General Hospital. Since 1970 he has been director of genetics at the Eunice Kennedy Shriver Center for Mental Retardation in Waltham, Mass. Trained in his native Johannesburg, South Africa, Dr. Milunsky became a member of the Royal College of Physicians in London before emigrating to the U.S. in 1966 (he became a citizen in 1971). He is the author of six books, including Know Your Genes (Avon, $1.95), written for prospective parents. Recently he explained to Gail Jennes of PEOPLE why he believes that with prenatal testing, "Women who postpone babies need run no greater risks of having children with birth defects or genetic disorders than younger women."
What is amniocentesis?
The procedure consists of inserting a small needle through the abdominal skin into the womb, or uterus, from which a tablespoon or two of the liquid surrounding the fetus is withdrawn. Suspended in this amniotic fluid are cells, some living, which have been naturally sloughed off from the fetus. By analyzing them, many prenatal diagnoses can be made, including, incidentally, the sex of the unborn.
Do women ask for amniocentesis just to determine whether it's a boy or girl?
No; in more than 10 years we have had only three such requests. We will not do amniocentesis for that purpose. Prenatal studies represent a scarce and expensive technology, and family planning is an inappropriate use of it.
How accurate is the procedure?
That depends on the expertise of the laboratory. In good laboratories, accuracy exceeds 99.4 percent.
What risks do older mothers run?
The chance of having babies with chromosome defects, including Down's syndrome or mongolism, becomes really significant at age 35, when the figure for genetic defects is close to one percent. At 40, the risk rises to three percent, and at 45 to 10 percent.
Is amniocentesis itself risky?
It is not a test to be undertaken on a whim. There should be good reasons for it. There is a risk that the needle introduced into the body cavity may introduce infection or cause bleeding or a miscarriage.
What are the chances of losing the baby?
Very small. A National Institutes of Health study suggests a figure below 0.5 percent is reliable. In good hands, it's closer to 0.2 to 0.3 percent.
When during pregnancy should such a test be made?
At 15 to 16 weeks into the pregnancy. If the physician waits much longer—18 to 19 weeks—there is almost no time for preventive abortion to be initiated if a serious defect is found.
Who should perform the test?
A qualified obstetrician experienced in the technique. It is best done in a hospital with ultrasound facilities, which can determine the exact location of placenta and fetus.
Is an anesthetic necessary?
Some obstetricians routinely give a local anesthetic, others use none at all. Some argue that the patient says "Ouch!" and then the test is essentially over. It takes just a few minutes.
How long must a couple wait to know the results of the test?
There is a two-to four-week waiting period while the cells are grown in a culture medium. They can then be examined under a microscope to determine if the correct number of chromosomes—46—is there. If the cell has an extra number, we can predict the genetic disorder. For instance, if there is an extra chromosome number 21, the offspring will have Down's syndrome.
Why do women 35 and over run greater risk in pregnancy?
It is not clear why. One theory suggests that both hereditary and environmental factors like X-rays make the chromosomes more sticky at the point of division when conception occurs. An extra chromosome hangs in and the person is born with one extra chromosome in every cell.
Who should consider amniocentesis?
Couples with a child born defective or with a history of genetically transmissible disease. One example is spina bifida, an open defect of the spine which causes paralysis of both legs, no bladder control and often retardation. Mothers of such children have said, "Never again!" But with the test they have had two or three more normal children.
So it eliminates fear that a baby will have certain defects?
Yes, and this is especially rewarding for a couple who have previously had a tragedy—a child with retardation or grotesque features. You can tell them for certain that their next baby does not have that condition.
How often does a couple face a decision to abort?
Only about two or three percent even have to consider the question.
Who makes the decision to abort?
I believe this is the parents' choice, not the doctor's. Physicians should not direct or coerce them. I believe parents have the right to know all the available information, and then they themselves should determine whether to continue or abort the pregnancy.
Can the father's age be a problem?
Yes, in certain genetic disorders. For example, fathers of circus dwarfs tend to be older—beyond 45. But the evidence in other chromosome disorders is contradictory.
Suppose the husband and wife disagree about abortion?
On these rare occasions, the courts have recognized that the woman has all the legal rights in this matter and that she can determine what to do.
What about those who say, "Many families have been advanced and enriched by having a defective child"?
For more than 20 years I have cared for families who have children with major birth defects and genetic disorders. The chaos, grief and economic shambles of such families are legion. It is not myth. It is real and devastating, not only for the parents but for the siblings, let alone the unbelievable suffering of the actual child.
How much does amniocentesis cost?
Nationally, costs range from $250 to $500, which includes laboratory tests, counseling and ultrasound. As a result, until recently, this tool has been for the upper-middle to high income group. You discover to your horror that the poor basically have few opportunities to have this test.
How many such tests are done?
The tardiness of the new technology is remarkable. In Massachusetts I would estimate close to 17 to 20 percent of women who need amniocentesis have it. Most states have a figure closer to five percent.
Why are the figures so low?
Lack of information provided to patients, and lack of information on the part of their own doctors. Physicians who graduated before 1960 had little formal genetic training and even in 1970 many medical schools did not provide full courses.
What about law cases in which the mother of a mongoloid child has sued, claiming her doctor did not inform her of the risk or about amniocentesis tests?
I am involved in at least a dozen lawsuits as an expert witness. I've been called both by plaintiffs and by defendants. The most common complaint is that physicians do not tell patients that these tests exist. The test is a minor surgical procedure, yet certain physicians, because of religious or other bias, warn patients that the procedure kills babies. This is a serious ethical problem.
What is the cost of rearing a defective child?
The lifetime care of a mongoloid child is estimated at $500,000. It is fallacious to argue that home care is the simple answer. In practice, the vast majority of severely defective people ultimately become a burden to the taxpayer.
Where should a woman go if she does not live near a major medical center?
She should speak with her obstetrician and if necessary seek a second opinion from a university medical center's department of obstetrics or genetics. It is worth traveling any number of hours for that advice and to travel that route one more time for the test. It may spare a lifetime of grief.
When will treatment inside the womb be possible?
There is only one case of a biochemical genetic disorder where the fetus was treated through the mother by the administration of vitamin B 12. The fetus and subsequently the child developed normally. With new genetic engineering tools we may ultimately talk about not only treatment of genetic disease but cure. But we are a long way from that state.