Does Medication Pass Through Placenta

Placental drug transfer. Almost all drugs will eventually cross the placenta to reach the fetus. In some cases, this transplacental transfer may be beneficial and drugs may be deliberately administered to the mother in order to treat specific fetal conditions.

Do all medications pass through the placenta?

Drugs with low molecular weight (<500 g/mol) diffuse freely across the placenta. Drugs with a higher molecular weight (between 500-1000 g/mol) cross the placenta less easily, while a few drugs with a high molecular weight (>1000 g/mol) do not cross the placental membrane[11].

What substances Cannot pass through the placenta?

Whether a substance may pass through the placenta between mother and fetus depends on its molecular size, shape, and charge. The substances not likely to pass in significant amounts include bacteria, heparin, sIgA, and IgM. Most antigens are small whereas IgM is a large molecule.