Babies in the womb are exposed to virtually every drug or substance which a pregnant woman takes, including herbs and alcohol. How can a pregnant woman know which are safe for her developing baby?
A substance which is capable of causing abnormal fetal development is a teratogen. Fortunately, the list of major teratogens is quite short and includes some anti-seizure drugs, oral blood thinners, Retin-A, alcohol and radiation.
The effect a teratogen has on a developing baby depends on the dose, when in pregnancy the substance is taken and on individual variation. Exposure must occur during the critical period of organ formation, two to eight weeks after fertilization (four to 10 weeks after the first day of the last menstrual period). Before this time exposure to a teratogen results in what is called the "all or none" effect: Either the embryo survives unharmed or is reabsorbed.
Some drugs can cause effects after the critical period of organ formation; for example, if the antibiotic tetracycline is taken after the 19th week of pregnancy it can cause permanent gray staining of the teeth.
If you are taking a medication which is known to be a major teratogen, you should always use an effective method to prevent pregnancy. If you plan to become pregnant, see your health care provider to discuss changing your medication before you try to conceive. Remember that many of the damaging effects to the baby can occur before you know that you are pregnant. Do not stop taking your medications without consulting your provider.
There is no known "safe" amount of alcohol consumption in pregnancy. The fetus is at greatest risk from chronic drinking and from "binge" drinking, but the only way to assure there is no damage is to avoid alcohol completely if you are pregnant or trying to conceive.
Exposure to X-ray can lead to pregnancy loss, birth defects and increase in childhood cancers; however it is important to remember that these effects are related to the amount of radiation and that most diagnostic X-rays do not come near the level that is dangerous to the developing baby. A single diagnostic procedure such as a chest X-ray is not thought to pose any risk to the fetus. If you are or may be pregnant your abdomen will be shielded with a lead apron to decrease exposure of the fetus. If multiple X-rays are needed an expert can calculate dosage in order to proceed safely.
Popular antidepressants of the SSRI category are getting a lot of attention as possible teratogens. Only one SSRI (Paxil) has been associated with an actual birth defect and should be avoided if pregnant or trying to conceive. The FDA has concluded that there is not sufficient evidence to withhold SSRIs from pregnant women or take them off of antidepressants.
Sixty percent of pregnant women self-medicate with over-the-counter drugs, vitamins and herbs. Do not assume that all of these are safe in pregnancy! Consult your provider for guidance.
Donna Ogg, a Certified Nurse-Midwife, is employed by Women's Care Partners, Altoona. She has 23 years of experience in her field. She lives in Hollidaysburg.