Pregnancy and Pills
New research finds prescriptions may be safer than you think
Ask any pregnant woman and she'll tell you she'd rather swallow a live goldfish than a prescription pill. Her obstetrician likely shares the sentiment--and with good reason. Both doctors and patients are haunted by the memory of babies born severely deformed when their mothers took thalidomide as a sedative in the late 1950s. And in 1971, diethylstilbestrol, or DES, was linked to a rare form of vaginal cancer in the daughters of women who had taken the medication while pregnant. The result of these scares has been a widespread reluctance by doctors to prescribe their expectant patients so much as a cough drop.
Yet when life-threatening or chronic diseases affect pregnant women, abstaining from pharmaceutical drugs can often be more risky to a developing fetus than taking medicine to treat the illness. And while caution is still the watchword when it comes to pregnancy and drugs, new research indicates that many medications aren't nearly as dangerous to unborn children as doctors once thought.
Knowledge gap. Chemotherapy, the administration of toxic drugs that kill cancer cells, is the latest example of a treatment that is surprisingly safe in pregnancy. A study in last month's Journal of Clinical Oncology looked at 24 pregnant women with breast cancer who received an average of four cycles of chemotherapy after a malignant tumor was removed. All of the women gave birth to healthy babies. The oldest of the children studied is now 10 years old, and so far, says lead investigator Richard Theriault of the University of Texas, "all signs point to normal."
In addition to the breast cancer findings, studies published in the New England Journal of Medicine and the Journal of the American Medical Association in the past two years show that antidepressants such as Prozac appear to be safe for use by pregnant women. The researchers conclude that there is no evidence of physical or cognitive abnormalities in children exposed to certain antidepressants when their mothers were pregnant. "Most common drug exposures do not pose a great risk to a fetus," says Lewis Holmes, head of the pediatrics service of the Genetics and Teratology Unit at the University of Massachusetts. "But most doctors don't know that."
Doctors are in the dark largely because they do not have good information on the safety of drugs for expectant mothers. Before the thalidomide debacle, the placenta had been viewed as a protective barrier between the mother and the fetus that allowed only good things to reach the baby. But after the thalidomide cases and other episodes proved that the placenta was penetrable, the Food and Drug Administration banned pharmaceutical research involving women of childbearing age, for fear of causing more reproductive harm.
The fear filtered down to physicians treating pregnant women with pre-existing conditions. Wendy Hennessy, of Huntley, Ill., has panic disorder, a condition treatable by antidepressant drugs. When her illness flared up during her first pregnancy three years ago, her psychiatrist refused to prescribe any medication. "Once I got pregnant," she says, "he wanted nothing to do with me."
Aging mothers. Recognizing the need to correct the situation, the FDA reversed its position in 1993 when it began requesting information from drug companies on how experimental drugs work in women. That information is seen as increasingly critical: As more and more women choose to have babies after age 40, the number of women who become pregnant with underlying medical conditions (currently 1 in 10) is expected to rise.
But seven years later, the system for collecting this vital medical information remains severely limited. Drugs are rated according to a system of alphabetical categories that in most cases only serve to tell the doctor that the safety of a drug isn't known. Adding to the uncertainty are drug companies that openly discourage contact between their products and pregnant women. Merck, for example, is currently running a television ad for its baldness drug Propecia that tells expectant mothers they literally should not touch crushed or broken tablets.
Experts in the field of teratology (the study of birth defects) say drug companies are sometimes too cautious. "Talk about hype," says Kathy Johnson, coordinator of the California Teratogen Information Service and Clinical Research Program. "This just heightens fear. Someone is going to touch [a Propecia pill] and is going to abort her baby over it."
Animal studies over the years have helped point researchers to potential problems with drugs in pregnant women, but they don't tell the whole story. And clinical trials on expectant mothers are considered unethical. So doctors rely on case reports of pregnant women who have used medications in the past. "When we get enough of that anecdotal experience [that a drug is safe], then people will start using it," says Dr. John Gianopoulos of Loyola University Medical Center in Chicago. For example, 30 years ago a woman with a seizure disorder would have been advised against pregnancy because both the seizures and the medication to treat the disorder were thought to be equally harmful for the fetus. But now, based on years of case reports, doctors know that the risk of birth defects from anticonvulsant drugs is relatively low.
That was good news for Lori Kim of South Orange, N.J., who suffers from a seizure disorder. She and her husband, a doctor, agreed that during her pregnancy she would continue using Tegretol, the medication that had kept her seizure free for years. She had a healthy baby, but only after an ultrasound in the 26th week brought a scare about birth defects.
But while fear of deformities may tempt a woman to stop taking her medication, diseases that are left untreated may do as much harm to a developing baby as a drug would. Asthma that goes untreated can deprive a fetus of oxygen, which can lead to low birth weight or even fetal death. A diabetic who does not control her blood sugar increases her odds of a problem pregnancy to 30 percent.
Mary Beth Barnes of Pasadena, Md., has had diabetes since she was 11 years old. Early in her first pregnancy, she injected herself with insulin but her blood sugar was not well managed. As a result, she says, her baby was born with a heart defect and died one month later. In later pregnancies, Barnes was vigilant about controlling her disease: She used an insulin pump to regulate her intake of the drug, and she ate meals and exercised at the same time every day. She is now the mother of three healthy boys.
Matters of time. Because it can take as long as 10 years for doctors to collect enough case reports to know whether a new drug is safe in pregnancy, drug companies and academic institutions are now using "pregnancy registries" to speed things up. They hope that these registries, which track women who have taken a specific drug, will cut the time it takes to collect data in half.
In the future, doctors may be able to prescribe "fetus friendly" drugs. At the University of Kansas, researchers are developing models of the human placenta that will allow them to figure out why certain drugs cross the placenta and others don't. One theory focuses on protein transporters that carry substances such as nutrients across the placenta to the fetus. One called P-glycoprotein acts as a barrier to many types of drugs trying to pass through. "We'd like to figure out what makes a drug able to be recognized by the protein, and [to] develop drugs that have that quality," says researcher Kenneth Audus. It will be at least five to 10 years before these drugs are available, he says.
In the meantime, there is no doubt that taking medications during pregnancy is risky and should only be done when medically necessary. Paulette Carter, a Long Beach, Miss., woman who was diagnosed with breast cancer 6 1/2 months into her pregnancy at age 32, is one patient who felt she had no choice. She underwent two rounds of chemotherapy in the experimental program for pregnant women at the University of Texas. "Not a minute went by," Carter says, "when I didn't fear that what I was doing was going to hurt my baby." As it turns out, Carter delivered a healthy baby girl. She is cancer free. And she is pregnant again.
This story appears in the April 5, 1999 print edition of U.S. News & World Report.