The Link Between Birth Defects and Medication

One cause of birth defects can be traced to medications ingested by the mom-to-be. There are several drugs that are known to cause birth defects if taken during pregnancy. Some medications have warnings on the label to advise pregnant women to not take them.

A study published in August of 2006, in the issue of Neurology, a scientific journal of the American Academy of Neurology stated that the epilepsy drug valproate is known to pose a higher risk for fetal death and also birth defects, more so than other commonly prescribed epilepsy drugs. Physicians prescribing for pregnant epileptic patients need to be aware of this information. According to the study, 20% of the pregnancies where valproate was used, there resulted death or birth defects of the skull, limb or brain with heart and lung problems also occurring.

In the study birth defect and death rates were lower for the drugs: phenytoin, carbamazepine and lamotrigine. These studies are consistent with other similar studies. It is important that this information be made available to pregnant women and those who treat them.

The connection between medication and fetal risk depends on several factors:

Type of drug

Dosage

How it is taken

Gestational age of the fetus

Response of fetus to the medication

Maternal diet and illness

Even women who avoid medication all together during pregnancy have a 4% chance for birth defects so avoiding medications will not necessarily mean that you can prevent all birth defects. Medication is certainly not the only cause of birth defects.

Known Teratogenic drugs that pose birth defect risk:

ACE inhibitors (angiotensin converting enzyme)

Angiotensin II antagonist

Isotretinoin (acne drug)

Alcohol

Cocaine

Vitamin A in high dose

Lithium

Male hormones

Certain Antibiotics

Certain anticonvulsant medications

Certain Cancer fighting medications

Certain rheumatic medications

Certain thyroid medications

Thalidomide

Warfarin (blood-thinning)

Diethylstilbestrol hormone (DES)

There are other teratogenic drugs that lack medical studies; even illegal ones such as cannabis and amphetamines that may also cause birth defects but have not had studies to show conclusively that they do.

Medications can receive risk classifications so that physicians can have guidelines for prescribing for pregnant women. Australia has such as medication risk classification system. They have different categories for medications that apply to recommended doses and how safe they are for pregnant women to take. Such a classification system would be helpful for physicians in all countries to be able to refer to when making medication decisions. The classifications include those drugs that have been proven to increase the risk for birth defect, drugs lacking in data for safety in pregnant women, those drugs where there have been animal studies showing an increased risk for birth defects. Other categories include such things as known drugs that cause birth defects but whose health benefit to the pregnant woman outweigh the risk to the fetus for birth defect, drugs that cause harm to the fetus without causing birth defects and whose effects can be reversed, and those drugs that have a high risk for causing birth defects and should not be used in pregnancy.