Pregnancy and medications

Taking various medications during the pregnancy period should depend on the condition of a pregnant woman as well as her future baby. Influence of most medications on the pregnancy and fetus development remains unknown, only some medicines were fully evaluated as to their possible harmful influence on the fetus.

Fetal defects resulting from taking some medicines is defined as so called teratogenic effects. The knowledge we posses so far in this matter is in most cases based on descriptions of single cases when fetal defects occurred.

The scope of this article do not allow for a full elaboration on the topic of safety of using medications when pregnant, I should therefore restrain myself to discuss only the most essential aspects of this problem.

It needs to be stressed that medications must be used with particular cautiousness in the first period of pregnancy duration, namely from the insemination, through the implantation of the fertilized egg until the development of the primordial fetal organs is completed, namely to the end of embryogenesis and organogenesis.

The beginning of this period falls in the first day after the period had stopped, therefore reaching for various medications should be considered accidental – it results from a fact that a woman is unaware of being pregnant. That is why it is important to reconsider taking medication by women of child-bearing age in the case when their period is late, as in this very moment the effect of many medications on the fetus proves to be very powerful.

In the later period of 12-16 week of pregnancy the teratogenic effect of some medication on the fetus results rather in minor damages to its body organs without the occurrence of severe fetal defects.

In the antenatal period and perinatal period there also exists possibility of harmful effects of medications on the fetus.

In the literature of medicine an example of such effect are emerging fetal heart defects when using anti-inflammatory medications from the group of prostaglandin inhibitors in the antenatal period. It is certain that the possibility of harmful effect of a medication to the fetus depends on the exposition time and dosage.

Medications absolutely contraindicated during pregnancy due to the fact that they cause damages in fetus:

• Medicines used in cancer treatment, cytostatics,psychoactive, antiepileptic medicines as well as antidepressants,radioactive isotopes,
• most medications used in blood coagulation disorders ,
• antimalaric medication from chinidine derivatives group,
• ergot derivatives (ergotamine),
• most of antihistamine medications.

Some antibiotics are known to have harmful effect i.e. tetracykline (tetracyklin) which cause limb and teeth defect, it is also contraindicated to use chloramfenicole sulfonamides.

To conclude, it’s needs to be said that using each medication during pregnancy should follow considering its possible harmful effect on the fetus and pregnancy course.

Each time before taking any medication a pregnant woman should consult its use with an obstetrician taking care of her pregnancy. All medications should be used during pregnancy

because of therapeutic indications, in the lowest effective dose and only in the shortest time allowing its effectiveness.

In the first trimester of pregnancy a golden rule should be limiting mediacation taking only to the therapeutic minimum. Strict adhering to the above rules should allow to limit the possible harmful effect used during pregnancy.

dr Dariusz Niksiński