An example of this would be Zoloft, an antidepressant drug that falls under the classification, Selective Serotonin Reuptake Inhibitor (SSRI), which is reported to be associated with certain birth defects such as septal heart and enlarged heart defects. Drugs under this SSRI classification prevent the re-absorption of serotonin, a compound that acts as a neurotransmitter that helps maintain a person's feeling of wellbeing. This is believed to counteract the negative feelings associated with mood disorders and depression.
When diagnosed with clinical depression, patients, even pregnant ones are given medication by their doctors. The United States Food and Drug Administration (FDA) classifies these drugs used by pregnant women under a pregnancy category to determine their safety.
FDA Pregnancy Category(taken from the FDA's official site)
There is no demonstration of a significant risk to the fetus in the first trimester as well as in the later trimesters of pregnancy according to studies.
There are no adequate studies in pregnant women but animal reproduction tests and observations have failed to establish a risk to the growing fetus.
Animal reproduction studies revealed some adverse effects on the fetus and there are no studies in human but the potential benefits justify the use of the medication in pregnant women in spite of the potential risks.
Evidence of human fetal risk is positive as per the adverse reaction data from investigational or marketing experience or studies in humans but still, potential benefits may warrant use of the drug in pregnant women despite potential risks.
Adequate and well-observed studies in animals and/ or humans have demonstrated abnormalities in the fetus and/or there is positive evidence of human fetal risk basing on the adverse reaction data from investigational or marketing experience, and the dangers involved in the use of the drug in pregnant women greatly outweigh potential benefits.
The FDA classifies Zoloft as a category C medicine where harm could be inflicted on the developing fetus but it is believed that the benefits are more substantial that its potential risks. Note that drugs under this category were not tested on any pregnant human female. Recently, studies reveal that several birth defects is caused by taking Zoloft during pregnancy. Your doctor is still the best person to talk to regarding these matters. You should raise these concerns and discuss them with your ob-gynecologist in order to address them appropriately.