Decreasing the Chance of Birth Defects
By Rebecca Williams for the FDA Consumer
When Tammy Troutman of Knoxville, Tenn., was planning her first pregnancy, she
had a good reason to be concerned about birth defects. Born with a mild form of
spina bifida, Troutman worried her child would also have the condition. So she
did what health-care experts say is the best first step toward preventing birth
defects: She visited her physician for an exam well before she and her husband
tried to conceive.
"Before I decided to have children, I went to the doctor to make sure
everything would be OK," Troutman remembers. He advised her to take a daily
multivitamin supplement containing folic acid, a B vitamin that would decrease
her chances of having a baby with spina bifida. Troutman took the vitamins for
five months before conceiving her son, Evan, who was born in August 1993 with a
normal, healthy spine.
"Even if he had been born with spina bifida," Troutman says, "I
felt secure knowing that I had done everything I could to prevent it."
Of the 4 million infants born annually in the United States, about 3 to 5
percent are born with birth defects, according to the March of Dimes. Birth
defects account for 20 percent of all infant deaths in the United States, more
than from any other single cause.
"For the majority of birth defects, the cause is unknown," says Franz
Rosa, M.D., a pediatrician with the Food and Drug Administration who monitors
reports of prescription drugs causing birth defects. Rosa cites a list of drugs
that are known to be birth-defect causing, but he says they only account for a
small percentage of all malformations.
"Thereís a lot we just donít know," Rosa says. "Most birth
defects are not preventable and mothers should not feel guilty about causing
defects that they really didnít. Worrying too much is not good for
What experts do know is that most birth defects occur in the first three months
of pregnancy, when the organs are forming. It is in these crucial first few
weeks - often before a woman even knows sheís pregnant - that an embryo is
most susceptible to teratogens, substances that can cause defects. However, some
birth defects do occur later in pregnancy as well.
"The key is what your life is like at the time you become pregnant,"
says Deborah Smith, M.D., an obstetrician and gynecologist in FDAís Office of
Womenís Health. "Are you getting enough folic acid, are you immune to
rubella, are you avoiding alcohol and smoking? These are some of the things we
know are important."
Despite the benefits of seeing a doctor before conceiving, only 26 percent of
women planning a pregnancy do so, according to the March of Dimes. Furthermore,
health experts estimate more than 50 percent of pregnancies are unplanned.
Thatís why a healthy lifestyle for all women who could become pregnant - even
if they donít intend to - is the best way to minimize the risk of birth
The maxim "You are what you eat" is sterling advice during the first
three months of pregnancy. Studies of women who had endured starvation during
World War II illustrate the importance of diet early in pregnancy. Contrary to
what researchers expected, it was not the babies born during food deprivation
that had the most malformations, but those conceived during food deprivation.
One nutrient known to prevent birth defects is folic acid, the B vitamin Tammy
Troutman took before her pregnancy. Folic acid is the chemical form of folate,
which is found in green leafy vegetables, citrus fruits, and legumes. Folate
aids in cell division, and taking extra folic acid reduces a womanís chance of
have a child with spina bifida and other abnormalities of the spine and brain.
Spina bifida occurs when the vertebrae do not close completely. It is one of
several conditions known as neural tube defects, because the neural tube is the
portion of the embryo that develops into the brain and spinal column.
In very mild cases, spina bifida causes few or minor problems, but in more
severe cases, the spinal cord protrudes through the vertebrae into a sac outside
the childís body. This impairs the childís mobility and other neurological
functions and requires surgery to repair the opening.
To help prevent neural tube defects, the U.S. Public Health Service has
recommended that all women of childbearing age who are capable of becoming
pregnant consume 0.4 milligrams (mg) of folic acid per day. (For pregnant or
lactating women, the daily value increases to 0.8 mg per day.) It is especially
important that women take in sufficient folate before they become pregnant.
FDA recently published regulations requiring manufacturers to add folic acid to
enriched grain products such as flour, noodles, bread, rolls, buns, farina,
cornmeal, grits, and rice by January 1998.
Although the main challenge in pregnancy is getting enough nutrients, too much
of a good thing is not good for a developing baby, either. Vitamins A and D are
the most notable examples. Both can be toxic at levels higher than the
recommended daily allowance.
Such levels are rarely reached through food intake; however, women taking
dietary supplements need to be aware of this risk and the amount of these
vitamins they are taking. Women who take vitamin and mineral supplements should
discuss with a health- care professional what vitamins are safe to continue
taking during pregnancy.
Only a few foods are completely off-limits during pregnancy. These include raw
or undercooked meat, such as "pink-in-the- middle" burgers, and raw or
undercooked seafood. Bacteria from these can cause severe food poisoning, which
is dangerous to a fetus and very unpleasant for the mother.
Soft drinks, coffee, tea, and other caffeinated drinks can be used in
moderation. Although large doses of caffeine have caused skeletal defects in
rats, one or two cups of coffee daily are not considered dangerous for
Alcohol should be avoided at all times during pregnancy because it leads to low
birth weight and can cause deformities as well. According to the March of Dimes,
alcohol is the most common known cause of fetal damage in the country and the
leading cause of preventable mental retardation.
Pregnant women who drink alcohol, especially in large amounts, put their babies
at risk for fetal alcohol syndrome, which causes growth retardation, facial
deformities such as a small head, thin upper lip, and small jaw bone, and
underdeveloped thymus gland, and mental deficiencies or developmental delays.
If a woman has had a glass or two of wine before finding out she was pregnant,
she probably has not harmed her child. But since no one knows the exact amount
of alcohol that is dangerous, itís best to avoid alcohol when pregnancy is
Healthy Mothers, Healthy Babies
A pregnant woman who has a serious medical condition may face a greater than
normal risk that her child will have a birth defect. Diabetes, for example, can
complicate a pregnancy in many ways.
Women who must take insulin daily to control their blood sugar are three or four
times more likely to have a baby with major birth defects than are other
mothers. That is not to say they should abandon insulin, however. Without it,
many diabetic women and their babies wouldnít survive pregnancy at all.
Birth defects among diabetics can be greatly reduced if women get their blood
sugar levels under control before becoming pregnant and strictly manage their
diets throughout pregnancy. Gestational diabetes, which develops during
pregnancy, can also be harmful to mother and child, but it can be controlled
through diet or medication.
Epilepsy also increases a womanís chance of having a baby with a birth defect.
Itís not clear whether the disease itself or the drugs used to control it
cause malformations, but in either case, the womanís neurologist and
obstetrician should work together to find the safest course of treatment for the
epilepsy and pregnancy.
Rubella, toxoplasmosis, cytomegalovirus, and syphilis can cause birth defects in
the infants of women who have these infectious diseases. Rubella infection
during early pregnancy can cause abnormalities of the heart, eyes and ears.
Any woman planning a pregnancy should be tested for rubella immunity and
vaccinated if necessary. She must wait three months after vaccination before
becoming pregnant, however, because the vaccine itself can endanger a developing
Toxoplasmosis is transmitted only through raw meat and cat feces, both of which
pregnant women should try to avoid. The disease causes malformations of the
brain, liver and spleen if a fetus becomes infected in the first trimester.
If the woman has syphilis, she should be treated with antibiotics before
pregnancy. If not treated by at least the fourth month, syphilis can cause bone
and tooth deformities in the baby, as well as nervous system and brain damage.
Cytomegalovirus (CMV) is a herpes virus that causes no real problemóand
sometimes not even symptomsófor adults and children. In pregnancy, however, it
can damage the fetusí brain, eyes or ears. Because most people contract the
infection, whose symptoms are much like a cold, when they are children, most
adults are immune to it. Pregnant women who do not know if theyíve had CMV and
who work with large groups of young children should discuss the situation with
their health- care provider.
Sometimes it is not a disease that causes birth defects, but the medication used
to treat it. Unfortunately, no one knows for certain how most drugs will affect
a developing fetus.
Historically, most women of childbearing age have been excluded from clinical
trials of new drugs, and, although that is changing, drug manufacturers are
understandably reluctant to involve pregnant women in clinical trials for new
drugs. Therefore, the effects of many drugs are not known until they are in
wider use after market approval.
To be on the safe side, a pregnant woman shouldnít take any drug unless it is
absolutely necessary and not until sheís checked with her health-care
provider. However, even physicians have little information when prescribing
medication for pregnant women.
What is know about most drugs in pregnancy is based iether on animal studies or
on reports of problems after the drug is on the market. To give guidance labout
pregnancy safety, FDA requires that manufacturers include in the professional
labeling for each drug which one of several categories, reflecting known or
unknown danger to the fetus, the drug is in. The categories also provide
guidance on weighing the benefits and risk of use in pregnancy.
Two examples: Taxol (paciltaxel), used to treat ovarian and breast cancer, may
in some instances be appropriate in pregnancy even though it causes birth
defects in animals and is therefore believed to cause fetal harm in humans. The
benefits of its use to fight life- threatening cancers may outweigh the
potential harm to a fetus.
Accutane (isotretinoin) should never be used in pregnancy. It is highly
effective for treating severe cystic acne, but it causes serious birth defects.
There are other drugs available to treat acne, and the disease is not
life-threatening to the mother.
Who Should Paint the Nursery?
Chemicals - whether itís paint in the nursery or exhaust fumes in a parking
garage - have long been suspected of causing birth defects. Itís important for
pregnant women to realize that most birth defects are not caused by a single
factor, nor are they usually caused by faint traces of toxins. Scientists
believe it takes a combination of factors to trigger a congenital malformation.
"Most birth defects have one or more genetic factors and one or more
environmental factors," explains Richard Leavitt, director of science
information at the March of Dimes.
Most of the chemicals a pregnant woman encounters pose little threat compared
with the harm in smoking, drinking alcohol, or eating a poor diet. "Most
environmental exposure is at a low level compared to things you put in your
mouth or inhale purposefully into your lungs," Leavitt says. "Public
health warnings are aimed at the many to help the relatively few avoid a
Daily, heavy exposure to chemicals may be dangerous, however. "If a
pregnant woman must work around fumes or chemicals, such as in a dry-cleaning
business, art studio, or factory, she should use glove, masks and adequate
ventilation. But if she just gets a whiff of dry-cleaning fluid while picking up
her laundry from the cleaner, thereís little need to worry," Leavitt
Some environmental toxins such as lead are best avoided at any time, but
especially during pregnancy. Scraping leaded paint off an old house window,
drinking water from a pipe soldered with lead, or drinking out of decorative
pottery containing lead can all potentially cause lead poisoning - and mental
retardation - in a fetus.
Radiation is also dangerous to developing babies. A pregnant woman who works in
an x-ray department of a hospital must take precautions to avoid exposure.
Elective dental x-rays should be postponed until delivery, and any non-pregnant
woman who has an x-ray should have her reproductive organs shielded with a lead
Taking hot baths, using saunas, or exercising in hot, humid weather can raise a
womanís core temperature and have the potential to cause birth defects,
especially in the first trimester. Lukewarm baths and moderate exercise are
And what about computers or video display terminals? Although they have at times
been accused of causing harm, thereís probably no need to worry. Recent
studies have not found any relationship between computer terminals and
And as for who should paint the nursery - todayís paints donít contain lead
and therefore probably arenít dangerous. But there are other reasons to find
someone else to do this task.
The repetitive motion of painting can be a strain on back muscles already under
pressure from the extra weight of pregnancy, and standing on your feet for hours
can make advanced pregnancy miserable. If someone else can do it, pass this
Of all the environmental harms, undoubtedly the most harmful is one women can
control - smoking. Although there is no evidence smoking causes birth defects,
it deprives the fetus of oxygen and leads to a number of problems.
If all pregnant women avoided smoking, the United States would see a 5 percent
reduction in miscarriages, a 20 percent reduction in low-birth-weight births,
and an 8 percent reduction in premature deliveries in this country, according to
the March of Dimes.
In the Family
Finally, a number of birth defects are inherited. They are usually triggered
when the child inherits a matching pair of disease-causing genes, one from each
parent. This is most often an issue for couples of similar ethnic or geographic
For example, African-American couples are most at risk for having a child with
sickle cell anemia. According to the March of Dimes, couples of Ashkenazic
Jewish or French Canadian descent may be carriers of Tay- Sachs disease. People
who know of genetic disorders in their families, or those who have already had
one child with a disorder are also at a greater risk, as are couples who are
closely related, such as first cousins. Genetic testing is available to
determine the risk of passing some genetic disorders to an unborn child. Once a
pregnancy begins, prenatal testing is available to detect a number of disorders,
Some genetic abnormalities, such as Down syndrome (a genetic abnormality that
causes mental retardation, short stature, and flattened features), increase with
the parentsí ages. Women over 35 are at higher risk of having a child with
Down syndrome - about 1 in 100 for a 40-year-old, compared to 1 in 10,000 for a
20-year-old mother or 3 in 1,000 for a 35-year-old mother. And itís not always
just the motherís age that matters. An estimated 25 percent of Down syndrome
cases can be attributed to increased age of the father.
Finally, itís important to remember that for most healthy women, the incidence
of birth defects is very low - less than 3 percent. And of malformations that do
occur, the most common are also the most treatable. Cleft palate and club foot,
two of the more common birth defects, can be surgically repaired. Many heart
malformations can be repaired with surgery so that children live normal lives.
For the most part, health experts say, a woman can do a lot to ensure the health
of her child by maintaining a healthy lifestyle.