A complex twist: treating the fetus through the pregnant woman
Some fetal conditions are treated through transplacental transfer of
drugs adding a complex layer on the safety of drugs. While the drug is
administered to the pregnant woman and has known maternal side effects,
the primary indication is to treat the underlying fetal condition. One
important condition is fetal arrythmia (i.e. supraventricular
tachycardia) in which studies have shown benefit in administering
digoxin, sotalol, and flecainide among other antiarrhythmic medications
[52]. In this unique circumstance often added maternal monitoring by
electrocardiogram is advised to balance maternal/fetal well-being.
Another example is prevention of congenital toxoplasmosis. Spiramycin, a
well-known macrolide, has shown to decrease transmission of
toxoplasmosis in a seropositive pregnant woman by 60%. Due to its
chemical properties, it tends to concentrate in the placenta and rarely
transfer to the fetus mitigating adverse effects and fetotoxicity
[53].